In linguistics, declension is the inflection of nouns, pronouns, adjectives, and articles to indicate number (at least singular and plural), case (nominative or subjective, genitive or possessive, etc.), and gender. A declension is also a group of nouns that follow a particular pattern of inflection.
Declension occurs in many of the world's languages, and features very prominently in many European languages. Old English was a highly inflected language, as befits its Indo-European and especially its Germanic linguistic ancestry, but its declensions greatly simplified as it evolved into Modern English.
Basic declension theory 
The following hypothetical English grammar demonstrates how declension works in practice. Assume that in English the subject of a sentence has the suffix -tee and the object takes the suffix -woo. Sentences would appear as follows:
- John-tee read an article-woo.
- My friend-tee saw fireworks-woo.
- The article-tee talked about language-woo.
- A business man-tee used his mobile-woo.
- The mobile-tee automatically called the last number-woo.
These examples show how simple declension works in action. Note that, since the subjects and objects are marked with suffixes, the word order can change. As English depends on word order to identify the subject and object, word order cannot change. In the following, the first sentence is the only way to express John reading his book. The second example has a different meaning.
- John read a book.
- A book read John.
However in our theoretical English with declensions, the word order can be changed but the meaning will remain the same as long as the subject and object are marked with the correct suffix.
- John-tee saw the high speed train-woo.
- The high speed train-woo saw John-tee.
Note that the suffixes remain the same even though the word order has changed. In many languages with declension, the word order is not important, however the declension is not optional and nouns must be marked. The following are hypothetical cases and suffixes that would be used in our declined English.
- using something as a tool -ash
- going to/in direction of -ak
- doing something with an object or person -pat
- addressing someone by their name -cake
The following sentences in this theoretical English will demonstrate how this would seem to us if there were declensions.
- John-tee went home-ak with his friend-pat.
- My father-tee wrote a book-woo with his computer-ash.
- Sarah-cake, would you-tee please bring me-ak a whisky-woo with ice-pat.
Note that these sentences could be written in any order and the meaning would stay the same:
- Mark-tee goes work-ak car-ash.
- Car-ash Mark-tee goes work-ak.
- Work-ak Mark-tee goes car-ash.
This word order is not possible in modern English as there are no cases or declension as in other languages. This means that in English, word order is essential to constructing coherent sentences.
This theoretical system of declension is relatively simple and is more or less how declension works in languages such as Hungarian. Other languages have a far more complicated set of declensions where the suffixes (or prefixes or infixes) change depending on the gender of the noun, the quantity of the noun and many other possible factors. There may also be irregular nouns where the declensions are unique for each word. In many languages, articles, demonstratives and adjectives are also declined. The following example demonstrates such declension in our theoretical English.
- The-tee big-tee man-tee saw a-woo big-woo bear-woo.
- Our-tee favourite-tee teacher-tee taught us-woo how to get to the-ak city-ak centre-ak.
Modern English 
In Modern English, nouns have distinct singular and plural forms; that is, they decline to reflect their grammatical number. (Consider the difference between book and books.) In addition, a few English pronouns have distinct nominative and objective forms; that is, they decline to reflect their relationship to a verb or preposition. (Consider the difference between he (subjective) and him (objective), as in "He saw it" and "It saw him"; similarly, consider "who", which is subjective, and the somewhat archaic objective "whom") Further, these pronouns and a few others have distinct possessive forms, such as his and whose. By contrast, nouns have no distinct nominative and objective forms, the two being merged into a single plain case. For example, chair does not change form between "the chair is here" (subject) and "I saw the chair" (direct object). Possession is shown by the clitic -'s attached to a possessive noun phrase, rather than by declension of the noun itself.
Gender is at best only weakly grammaticalized in Modern English. While masculine, feminine, and neuter genders are recognized, nouns do not normally decline for gender, though some nouns, especially Latin words and personal names, exist in multiple forms corresponding to different genders: Alumnus (masculine, singular)/Alumna (feminine, singular); Andrew/Andrea, Paul/Paula, etc. Suffixes such as -ess, -ette, and -er can also derive overtly gendered versions of nouns, with marking for feminine being much more common than marking for masculine. Many nouns can actually function as members of two genders or even all three, and the gender classes of English nouns are usually determined by their agreement with pronouns, rather than marking on the nouns themselves.
Adjectives are rarely declined for any purpose. They can be declined for number when they are used as substitutes for nouns (as in, "I'll take the reds", meaning "I'll take the red ones" or as shorthand for "I'll take the red wines", for example). Some adjectives borrowed from other languages are, or can be, declined for gender, at least in writing: blond (male) and blonde (female) or a bonie lad as compared to a bonnie lass. Adjectives are not declined for case in Modern English, though they were in Old English. The article is never regarded as declined in Modern English, although technically the words this and that, and their plural forms these and those, are modern forms of the as it was declined in Old English.
- homo (nominative) "[the] man" [as a subject] (e.g., homo ibi stat the man is standing there)
- hominis (genitive) "of [the] man" [as a possessor] (e.g., nomen hominis est Claudius the man's name is Claudius)
- hominī (dative) "to [the] man" [as an indirect object] (e.g., homini donum dedi I gave a present to the man; homo homini lupus est Man is a wolf to man.)
- hominem (accusative) "[the] man" [as a direct object] (e.g., ad hominem toward the man, in the sense of argument directed personally; hominem vidi I saw the man)
- homine (ablative) "[the] man" [in various uses not covered by the above] (e.g., sum altior homine I am taller than the man).
There are two further noun cases in Latin, the vocative and the locative. The vocative case indicates that a person or thing is being addressed (e.g., O Tite, cur ancillam pugnas? O Titus, why do you fight the slave girl?). Though widely used, it differs in form from the nominative only in the masculine singular of the second declension (that is, never in the plural, never in the feminine or neuter, and never in any declension other than the second). The locative case is rare in classic Latin, and it is mostly adsorbed in the genitive case.
Sanskrit has eight cases: nominative, vocative, accusative, genitive, dative, ablative, locative and instrumental. Some count vocative not as a separate case, despite it having a distinctive ending in the singular, but consider it as a different use of the nominative.
- agent (kartṛ, related to the nominative)
- patient (karman, related to the accusative)
- means (karaṇa, related to the instrumental)
- recipient (sampradāna, related to the dative)
- source (apādāna, related to the ablative)
- locus (adhikaraṇa, related to the locative)
- address (sambodhan, related to the vocative)
For example, consider the following sentence:
vṛkṣ-āt parṇ-aṁ bhūm-āu patati from the tree a leaf to the ground falls
Here leaf is the agent, tree is the source, and ground is the locus. The endings -aṁ, -at, -āu mark the cases associated with these meanings.
See also 
Declension in specific languages 
- Arabic ʾIʿrab
- Basque declension
- Czech declension
- Dutch declension system
- Finnish language noun cases
- German declension
- Greek declension
- Icelandic declension
- Irish declension
- Latin declension
- Latvian declension
- Lithuanian declension
- Middle English declension
- Old English declension
- Polish declension
- Russian declension
- Slovak declension
- Slovenian declension
- Ukrainian declension
Latin and Greek 
Related topics 
- James Clackson (2007) Indo-European linguistics: an introduction, p.90
- Amba Kulkarni and Peter Scharf (eds), Sanskrit Computational Linguistics: First and Second International Symposia Rocquencourt, France, October 29-31, 2007 and Providence, RI, USA, May 15-17, 2008, Revised Selected Papers, Volume 5402 of Lecture notes in artificial intelligence, Springer, 2009, ISBN 3-642-00154-8, pp. 64–68.
- Pieter Cornelis Verhagen, Handbook of oriental studies: India. A history of Sanskrit grammatical literature in Tibet, Volume 2, BRILL, 2001, ISBN 90-04-11882-9, p. 281.
|Look up declension in Wiktionary, the free dictionary.|
- The Status of Morphological Case in the Icelandic Lexicon by Eiríkur Rögnvaldsson. Discussion of whether cases convey any inherent syntactic or semantic meaning.
- Optimal Case: The Distribution of Case in German and Icelandic by Dieter Wunderlich