Infinitive is a grammatical term used to refer to certain verb forms that exist in many languages. As with many linguistic concepts, there is not a single definition applicable to all languages. The word is derived from Late Latin infinitivus, a derivative of infinitus meaning "infinite". Infinitives are used mostly as non-finite verbs.
In traditional descriptions of English, the infinitive is the basic dictionary form of a verb when used non-finitely, with or without the particle to. Thus to go is an infinitive, as is go in a sentence like "I must go there" (but not in "I go there", where it is a finite verb). The form without to is called the bare infinitive, and the form with to is called the full infinitive or to-infinitive.
In many other languages the infinitive is a single word, often with a characteristic inflective ending, such as manger ("(to) eat") in French, portare ("(to) carry") in Latin, lieben ("(to) love") in German, etc. However some languages do not have any forms identifiable as infinitives. Many Native American languages and some languages in Africa and Australia do not have direct equivalents to infinitives or verbal nouns; in their place they use finite verb forms in ordinary clauses or various special constructions.
As a verb, an infinitive may take objects and other complements and modifiers to form a verb phrase (called an infinitive phrase). Like other non-finite verb forms (such as participles, gerunds and gerundives) infinitives do not generally have an expressed subject; thus an infinitive verb phrase also constitutes a complete non-finite clause, called an infinitive (infinitival) clause. Such phrases or clauses may play a variety of roles within sentences, often as nouns (for example as the subject of a sentence or as a complement of another verb), and sometimes as adverbs or other types of modifier. Infinitives are not usually inflected for tense, person, etc. as finite verbs are, although some degree of inflection sometimes occurs; for example Latin has distinct active and passive infinitives.
Infinitive phrases and clauses 
An infinitive phrase is a verb phrase constructed with the verb in infinitive form. This consists of the verb together with its objects and other complements and modifiers. Some examples of infinitive phrases in English are given below – these may be based on either the full infinitive (introduced by the particle to) or the bare infinitive (without the particle to).
- (to) sleep
- (to) write ten letters
- (to) go to the store for a pound of sugar
Since an infinitive does not normally take an expressed grammatical subject, an infinitive phrase effectively constitutes an entire clause. Viewed in this way, it is called an infinitive clause or infinitival clause, and is one of the types of non-finite clause. Such a clause can then play various grammatical roles as a constituent of a larger clause or sentence; for example it may serve as a noun phrase or adverb. Clauses may be embedded within each other in complex ways, as in the sentence:
- I want to tell you that John is going to get married.
Here the infinitival clause to get married is contained within the finite dependent clause that John is going to get married; this in turn is contained within another infinitival clause, which is contained in the finite independent clause (the whole sentence).
The grammatical structure of an infinitival clause may differ from that of a corresponding finite clause. For example, in German, the infinitive form of the verb usually goes to the end of its clause, whereas a finite verb (in an independent clause) typically comes in second position.
Marking for tense, aspect and voice 
In some languages, infinitives may be marked for grammatical categories such as voice, aspect, and to some extent tense. This may be done by inflection, as with the Latin perfect and passive infinitives, or by periphrasis (with the use of auxiliary verbs), as with the Latin future infinitives or the English perfect and progressive infinitives.
English has infinitive constructions which are marked (periphrastically) for aspect: perfect, progressive (continuous), or a combination of the two (perfect progressive). These can also be marked for passive voice (as can the plain infinitive):
- (to) eat (plain infinitive, active)
- (to) be eaten (passive)
- (to) have eaten (perfect active)
- (to) have been eaten (perfect passive)
- (to) be eating (progressive active)
- (to) be being eaten (progressive passive)
- (to) have been eating (perfect progressive active)
- (to) have been being eaten (perfect progressive passive, not often used)
Further constructions can be made with other auxiliary-like expressions, such as (to) be going to eat or (to) be about to eat, which have future meaning. For more examples of the above types of construction, see Uses of English verb forms: Perfect and progressive non-finite constructions.
Perfect infinitives are also found in other European languages which have perfect forms with auxiliaries similarly to English. For example, avoir mangé means "(to) have eaten" in French.
Regarding English, the term "infinitive" is traditionally applied to the unmarked form of the verb when used as a non-finite verb, whether or not introduced by the particle to. Hence sit and to sit, as used in the following sentences, would each be described as an infinitive:
- I can sit here all day.
- I want to sit on the other chair.
The form without to is called the bare infinitive; the form introduced by to is called the full infinitive or to-infinitive.
The other non-finite verb forms in English are the gerund or present participle (the -ing form), and the past participle – these are not referred to as infinitives. Moreover the unmarked form of the verb is not regarded as an infinitive when it is used as a finite verb: as a present indicative ("I sit every day"), subjunctive ("I suggest that he sit"), or imperative ("Sit down!"). (For some irregular verbs the form of the infinitive coincides additionally with that of the past tense and/or past participle, as in the case of put.)
Certain auxiliary verbs are defective in that they do not have infinitives (or any other non-finite forms). This applies to the modal verbs (can, must, etc.), as well as certain related auxiliaries such as the had of had better and the used of used to. (Periphrases can be used instead in some cases, such as (to) be able to for can, and (to) have to for must.) It also applies to the auxiliary do, as used in questions, negatives and emphasis as described under do-support. (Infinitives are negated by simply preceding them with not. Of course the verb do when used as a main verb can appear in the infinitive.) However, the auxiliary verbs have (used to form the perfect) and be (used to form the passive voice and continuous aspect) both commonly appear in the infinitive: "I should have finished by now"; "It's thought to have been a burial site"; "Let him be released"; "I hope to be working tomorrow."
A matter of controversy among prescriptive grammarians and style writers has been the appropriateness of separating the two words of the to-infinitive (as in "I expect to happily sit here"). For details of this, see split infinitive. Modern linguistic theories typically do not consider the to-infinitive to be a distinct constituent, instead regarding the particle to as operating on an entire verb phrase; so, to buy a car is parsed as to [buy [a car]], not as [to buy] [a car].
Huddleston and Pullum's Cambridge Grammar of the English Language (2002) does not use the notion of the "infinitive", only that of the infinitival clause, noting that English uses the same form of the verb, the plain form, in infinitival clauses that it uses in imperative and present-subjunctive clauses.
Uses of the infinitive 
The bare infinitive and the to-infinitive have a variety of uses in English. The two forms are mostly in complementary distribution – certain contexts call for one, and certain contexts for the other; they are not normally interchangeable, except in occasional instances such as after the verb help, where either can be used.
The main uses of infinitives (or infinitive phrases) are as follows:
- As complements of other verbs. The bare infinitive is used as complement of the dummy auxiliary do, most modal auxiliary verbs, verbs of perception such as see, watch and hear (after a direct object), and the verbs of permission or causation make, bid, let, and have (also after a direct object). The to-infinitive is used after many intransitive verbs such as want, aim, like, fail, etc., and as a second complement after a direct object in the case of verbs such as want, convince, aim, etc.
- In various particular expressions, such as had better and would rather (with bare infinitive), in order to, as if to, am to/is to/are to.
- As a noun phrase, expressing its action or state in an abstract, general way, used as the subject of a clause or as a predicative expression: "To err is human"; "To know me is to love me". The bare inifinitive can be used in such sentences as "What you should do is make a list." A common construction with the to-infinitive involves a dummy pronoun subject (it), with the infinitive phrase placed after the predicate: "It was nice to meet you."
- Adverbially, to express purpose, intent or result – the to-infinitive can have the meaning of "in order to ..." or "so as to ...".
- As a modifier of a noun or adjective. This may relate to the meaning of the noun or adjective ("a request to see someone"; "keen to get on"), or it may form a type of non-finite relative clause, as in "the man to save us"; "the method to use"; "nice to listen to".
- In elliptical questions (direct or indirect): "I don't know where to go." After why the bare infinitive is used: "Why reveal it?"
In many (though not all) uses of the to-infinitive, it can be given a subject using the preposition for: "For him to fail now would be a great disappointment"; "[In order] for you to get there on time, you'll need to leave now."
The infinitive is also the usual dictionary form or citation form of a verb. The form listed in dictionaries is the bare infinitive, although the to-infinitive is often used in referring to verbs or in defining other verbs: "The word 'amble' means 'to walk slowly'"; "How do we conjugate the verb to go?"
Other Germanic languages 
In German it is -en ("sagen"), with -eln or -ern endings on a few words based on -l or -r roots ("segeln", "ändern"). The use of zu with infinitives is similar to English to, but is less frequent than in English. German infinitives can function as nouns, often expressing abstractions of the action, in which case they are of neuter gender: das Essen means the eating, but also the food.
In Dutch infinitives also end in -en (zeggen — to say), sometimes used with te similar to English to, e.g. "Het is niet moeilijk te begrijpen" → "It is not hard to understand." The few verbs with stems ending in -a have infinitives in -n (gaan — to go, slaan — to hit). Afrikaans has lost the distinction between the infinitive and present forms of verbs, with the exception of the verbs "wees" (to be), which admits the present form "is", and the verb "hê" (to have), whose present form is "het".
In North Germanic languages the final -n was lost from the infinitive as early as 500–540 AD, reducing the suffix to -a. Later it has been further reduced to -e in Danish and some Norwegian dialects (including the written majority language bokmål). In the majority of Eastern Norwegian dialects and a few bordering Western Swedish dialects the reduction to -e was only partial, leaving some infinitives in -a and others in -e (å laga vs. å kaste). In northern parts of Norway the infinitive suffix is completely lost (å lag’ vs. å kast’) or only the -a is kept (å laga vs. å kast’). The infinitives of these languages are inflected for passive voice through the addition of -s or -st to the active form. This suffix appeared in Old Norse as a contraction of mik (“me”, forming -mk) or sik (reflexive pronoun, forming -sk) and was originally expressing reflexive actions: (hann) kallar (“(he) calls”) + -sik (“himself”) > (hann) kallask (“(he) calls himself”). The suffixes -mk and -sk later merged to -s, which evolved to -st in the western dialects. The loss or reduction of -a in active voice in Norwegian did not occur in the passive forms (-ast, -as), except for some dialects that have -es. The other North Germanic languages have the same vowel in both forms.
Latin and Romance languages 
The formation of the infinitive in the Romance languages reflects that in their ancestor, Latin, almost all verbs had an infinitive ending with -re (preceded by one of various thematic vowels). For example, in Italian infinitives end in -are, -ere, -rre (rare), or -ire, and in -arsi, -ersi, -rsi, -irsi for the reflexive forms. In Spanish and Portuguese, infinitives end in -ar, -er, or -ir, while similarly in French they typically end in -re, -er, oir, and -ir. In Romanian the so-called "long infinitives" end in -are, -ere, -ire and they are converted into verbal nouns by articulation (verbs that cannot be converted into the nominal long infinitive are very rare). The "short infinitives" used in verbal contexts (e.g. after an auxiliary verb) have the endings -a,-ea, -e, and -i (basically removing the ending in "-re"). In Romanian, the infinitive is usually replaced by a clause containing the preposition sǎ plus the subjunctive mood. The only verb that is modal in common modern Romanian is the verb a putea, to be able to. But in popular speech, the infinitive after a putea is also increasingly replaced by the subjunctive.
In all Romance languages, infinitives can also be used as nouns.
Latin infinitives challenged several of the generalizations about infinitives. They did inflect for voice (amare, "to love", amari, to be loved) and for aspect (amare, "to love", amavisse, "to have loved"), and allowed for an overt expression of the subject (video Socratem currere, "I see Socrates running"). See Latin conjugation: Infinitives.
Romance languages inherited from Latin the possibility of an overt expression of the subject (as in Italian vedo Socrate correre). Moreover, the "inflected infinitive" (or "personal infinitive") found in Portuguese and Galician inflects for person and number. These are the only Indo-European languages that allow infinitives to take person and number endings. This helps to make infinitive clauses very common in these languages; for example, the English finite clause in order that you/she/we have... would be translated to Portuguese as para teres/ela ter/termos... (Portuguese is a null-subject language). The Portuguese personal infinitive has no proper tenses, only aspects (imperfect and perfect), but tenses can be expressed using periphrastic structures. For instance, even though you sing/have sung/are going to sing could be translated to apesar de cantares/teres cantado/ires cantar.
Other Romance languages (including Spanish, Romanian, Catalan, and some Italian dialects) allow uninflected infinitives to combine with overt nominative subjects. For example, Spanish al abrir yo los ojos ("when I opened my eyes") or sin yo saberlo ("without my knowing about it").
Hellenic languages 
Ancient Greek 
In Ancient Greek the infinitive has four tenses (present, future, aorist, perfect) and three voices (active, middle, passive). Unique forms for the middle are found only in the future and aorist; in the present and perfect, middle and passive are the same.
Modern Greek 
||This section needs attention from an expert in Greece. (March 2011)|
Only the Ancient Greek aorist infinitives active and passive survive in Modern Greek, but their descendants have a totally different function. The Ancient Greek γράψαι "to write" became γράψειν in analogy to the present infinitive γράφειν and then γράψει in Modern Greek and is used only in combination with the auxiliary verb έχω "I have" in the formation of the Present Perfect: έχω γράψει "I have written, lit. I have write(inf.)". When combined with είχα "I had", it yields the Past Perfect είχα γράψει "I had written". Similarly, the Ancient Greek γραφῆναι "to be written" survives as γραφεί (γραφῆ in Katharevousa); thus, έχει γραφεί (ἔχει γραφῆ in Kath.) means "It has been written".
In Pontic Greek, infinitives have a similar function; they only serve for the creation of the Present Perfect Optative: ας είχα γράψ'ναι "I wish I have written". Infinitives are formed this way: active: root of the Future + -ναι; passive: root of the Aorist + -θήν. Examples: εποθανείναι, μαθείναι, κόψ'ναι, ράψ'ναι, χαρίσ'ναι, αγαπέθην, κοιμεθήν.
In Modern Greek, "I want to write" translates θέλω να γράψω (literally, "I want that I write"), opposed to Ancient Greek ἐθέλω γράφειν (literally, "I want to write"). In Modern Greek, the infinitive has changed form and is used mainly in the formation of tenses and not with an article or alone. Instead of the Ancient Greek infinitive "γράφειν", Modern Greek uses the infinitive "γράψει", which does not inflect. The Modern Greek infinitive has only two forms according to voice, "γράψει" for the active voice and "γραφ(τ)εί" for the passive voice.
Balto-Slavic languages 
The infinitive in Russian usually ends in -t’ (ть) preceded by a thematic vowel, or -ti (ти), if not preceded by one; some verbs have a stem ending in a consonant and change the t to č’, such as *mogt’ → moč’ (*могть → мочь) "can". Some other Balto-Slavic languages have the infinitive typically ending in, for example, -ć (sometimes -c) in Polish, -t’ in Slovak, -t (formerly -ti) in Czech and Latvian (with a handful ending in -s on the latter), -ty (-ти) in Ukrainian, -ць (-ts') in Belarusian. Lithuanian infinitives end in -ti, Slovenian end on -ti or -či, and Croatian on -ti or -ći.
Serbian officially retains infinitives -ti or -ći, but is more flexible than the other Slavs in breaking the infinitive through a clause. The infinitive nevertheless remains the dictionary form. Bulgarian and Macedonian have lost the infinitive altogether (it usually ended in -ти). For that reason, the present first-person singular conjugation is used as the dictionary form in Bulgarian, where as Macedonian uses the third person singular form of the verb in present tense.
Biblical Hebrew 
Hebrew has two infinitives, the infinitive absolute and the infinitive construct. The infinitive construct is used after prepositions and is inflected with pronominal endings to indicate its subject or object: bikhtōbh hassōphēr "when the scribe wrote", ahare lekhtō "after his going". When the infinitive construct is preceded by ל (lə-, li-, lā-) "to", it has a similar meaning as the English to-infinitive, and this is its most frequent use in Modern Hebrew. The infinitive absolute is used for verb focus, as in מות ימות mōth yāmūth (literally "die he will die"; figuratively, "he shall indeed die"). This usage is commonplace in the Bible, but in Modern Hebrew it is restricted to high-flown literary works.
Note, however, that the to-infinitive of Hebrew is not the dictionary form; that is the third person singular perfect form.
To form the first infinitive, the strong form of the root (without consonant gradation or epenthetic 'e') is used, and these changes occur:
- the root is suffixed with -ta/-tä according to vowel harmony
- consonant elision takes place if applicable, e.g. juoks+ta → juosta
- assimilation of clusters violating sonority hierarchy if applicable, e.g. nuol+ta → nuolla, sur+ta → surra
- 't' weakens to 'd' after diphthongs, e.g. juo+ta → juoda
- 't' elides if intervocalic, e.g. kirjoitta+ta → kirjoittaa
As such, it is inconvenient for dictionary use, because the imperative would be closer to the root word. Nevertheless, dictionaries use the first infinitive.
There are also four other infinitives, plus a "long" form of the first:
- The long first infinitive is -kse- and must have a personal suffix appended to it. It has the general meaning of "in order to [do something], e.g. kirjoittakseni "in order for me to write [something]".
- The second infinitive is formed by replacing the final -a/-ä of the first infinitive with e. It can take the inessive and instructive cases to create forms like kirjoittaessa "while writing".
- The third infinitive is formed by adding -ma to the first infinitive, which alone creates an "agent" form: kirjoita- becomes kirjoittama. The third infinitive is technically a noun (denoting the act of performing some verb), so case suffixes identical to those attached to ordinary Finnish nouns allow for other expressions using the third infinitive, e.g. kirjoittamalla "by writing".
- A personal suffix can then be added to this form to indicate the "agent participle", such that kirjoittamani kirja = "the book which I wrote".
- The fourth infinitive adds -minen to the first, forming a noun which has the connotation of "the process of [doing something]", e.g. kirjoittaminen "[the process of] writing". It, too, can be inflected like other Finnish nouns which end in -nen.
- The fifth infinitive adds -maisilla- to the first, and like the long first infinitive, must take a possessive suffix. It has to do with being "about to [do something]" and may also imply that the act was cut off or interrupted, e.g. kirjoittamaisillasi "you were about to write [but something interrupted you]". This form is more commonly replaced by the third infinitive in adessive case, usually also with a possessive suffix (thus kirjoittamallasi).
Note that all of these must change to reflect vowel harmony, so the fifth infinitive (with a third-person suffix) of hypätä "jump" is hyppäämäisillään "he was about to jump", not *hyppäämaisillaan.
The Seri language of northwestern Mexico has infinitival forms which are used in two constructions (with the verb meaning 'want' and with the verb meaning 'be able'). The infinitive is formed by adding a prefix to the stem: either iha- [iʔa-] (plus a vowel change of certain vowel-initial stems) if the complement clause is transitive, or ica- [ika-] (and no vowel change) if the complement clause is intransitive. The infinitive shows agreement in number with the controlling subject. Examples are: icatax ihmiimzo 'I want to go', where icatax is the singular infinitive of the verb 'go' (singular root is -atax), and icalx hamiimcajc 'we want to go', where icalx is the plural infinitive. Examples of the transitive infinitive: ihaho 'to see it/him/her/them' (root -aho), and ihacta 'to look at it/him/her/them' (root -oocta).
Translation to languages without an infinitive 
In languages without an infinitive, the infinitive is translated either as a that-clause or as a verbal noun. For example, in Literary Arabic the sentence "I want to write a book" is translated as either urīdu an aktuba kitāban (lit. "I want that I write a book", with a verb in the subjunctive mood) or urīdu kitābata kitābin (lit. "I want the writing of a book", with the masdar or verbal noun), and in Levantine Colloquial Arabic biddi aktub kitāb (subordinate clause with verb in subjunctive).
Even in languages that have infinitives, similar constructions are sometimes necessary where English would allow the infinitive. For example, in French the sentence "I want you to come" translates to Je veux que vous veniez (lit. "I want that you come", with come being in the subjunctive mood). However, "I want to come" is simply Je veux venir, using the infinitive, just as in English. In Russian, sentences such as "I want you to leave" do not use an infinitive. Rather, they use the conjunction чтобы "in order to/so that" with the past tense form (most probably remnant of subjunctive) of the verb: Я хочу, чтобы вы ушли (literally, "I want so that you left").
See also 
|Look up infinitive in Wiktionary, the free dictionary.|
- Pană Dindelegan, Gabriela. "Aspecte ale substantivizării în româna actuală. Forme de manifestare a substantivizării adjectivului" (in Romanian). p. 2.
- Kim Schulte (1994), Pragmatic Causation in the Rise of the Romance Prepositional Infinitive: A statistically-based study with special reference to Spanish, Portuguese and Romanian.[dead link] PhD Dissertation, University of Cambridge.
- Scott N. Callaham, Modality and the Biblical Hebrew Infinitive Absolute, Abhandlungen für die Kunde des Morgenlandes 71 (Wiesbaden: Harrassowitz, 2010).