In grammar, a conjunction (abbreviated CONJ or CNJ) is a part of speech that connects words, sentences, phrases, or clauses. A discourse connective is a conjunction joining sentences. This definition may overlap with that of other parts of speech, so what constitutes a "conjunction" must be defined for each language. In general, a conjunction is an invariable grammatical particle, and it may or may not stand between the items it conjoins.
The definition may also be extended to idiomatic phrases that behave as a unit with the same function, eg "as well as", "provided that".
A simple literary example of a conjunction: "the truth of nature, and the power of giving interest" (Samuel Taylor Coleridge's Biographia Literaria)
There is some dispute over whether or not a conjunction should be placed at the beginning of a sentence in formal writing.
Coordinating conjunctions, also called coordinators, are conjunctions that join, or coordinate, two or more items (such as words, main clauses, or sentences) of equal syntactic importance. In English, the mnemonic acronym FANBOYS can be used to remember the coordinators for, and, nor, but, or, yet, and so. These are not the only coordinating conjunctions; various others are used, including:ch. 9:p. 171 "and nor" (British), "but nor" (British), "or nor" (British), "neither" ("They don't gamble; neither do they smoke"), "no more" ("They don't gamble; no more do they smoke"), and "only" ("I would go, only I don't have time"). Types of coordinating conjunctions include cumulative conjunctions, adversative conjunctions, alternative conjunctions, and illative conjunctions.
Here are some examples of coordinating conjunctions in English and what they do:
- presents rationale ("They do not gamble or smoke, for they are ascetics.")
- presents non-contrasting item(s) or idea(s) ("They gamble and they smoke.")
- presents a non-contrasting negative idea ("They do not gamble, nor do they smoke.")
- presents a contrast or exception ("They gamble, but they don't smoke.")
- presents an alternative item or idea ("Every day they gamble or they smoke.")
- presents a contrast or exception ("They gamble, yet they don't smoke.")
- presents a consequence ("He gambled well last night so he smoked a cigar to celebrate.")
- not only...but (also)
- just as...so
- no sooner...than
- You either do your work or prepare for a trip to the office.
- Not only is he handsome, but he is also brilliant.
- Neither the basketball team nor the football team is doing well.
- Both the cross country team and the swimming team are doing well.
- Whether you stay or you go, it's your decision.
- Just as many Americans love basketball, so many Canadians love ice hockey.
- The more you practice dribbling, the better you will get at it.
- Football is as fun as hockey.
- No sooner did she learn to ski, than the snow began to thaw.
- I would rather swim than surf.
Subordinating conjunctions, also called subordinators, are conjunctions that join an independent clause and a dependent clause, and also introduce adverb clauses. The most common subordinating conjunctions in the English language include after, although, as, as far as, as if, as long as, as soon as, as though, because, before, even if, even though, every time, if, in order that, since, so, so that, than, though, unless, until, when, whenever, where, whereas, wherever, and while.
Complementizers can be considered to be special subordinating conjunctions that introduce complement clauses: e.g. "I wonder whether he'll be late. I hope that he'll be on time". Some subordinating conjunctions (until and while), when used to introduce a phrase instead of a full clause, become prepositions with identical meanings.
The subordinating conjunction performs two important functions within a sentence: illustrating the importance of the independent clause and providing a transition between two ideas in the same sentence by indicating a time, place, or cause and thus effecting the relationship between the clauses.
In many verb-final languages, subordinate clauses must precede the main clause on which they depend. The equivalents to the subordinating conjunctions of non-verb-final languages such as English are either
- clause-final conjunctions (e.g. in Japanese); or
- suffixes attached to the verb, and not separate words
Such languages often lack conjunctions as a part of speech, because:
- the form of the verb used is formally nominalised and cannot occur in an independent clause
- the clause-final conjunction or suffix attached to the verb is a marker of case and is also used in nouns to indicate certain functions. In this sense, the subordinate clauses of these languages have much in common with postpositional phrases.
In other West Germanic languages like German and Dutch, the word order after a subordinating conjunction is different from that in an independent clause, e.g. in Dutch want ("for") is coordinating, but omdat ("because") is subordinating. The clause after the coordinating conjunction has normal word order, but the clause after the subordinating conjunction has verb-final word order. Compare:
- Hij gaat naar huis, want hij is ziek. ("He goes home, for he is ill.")
- Hij gaat naar huis, omdat hij ziek is. ("He goes home, because he is ill.")
Similarly, in German, "denn" (for) is coordinating, but "weil" (because) is subordinating:
- Er geht nach Hause, denn er ist krank. ("He goes home, for he is ill.")
- Er geht nach Hause, weil er krank ist. ("He goes home, because he is ill.")
Starting a sentence
Although many students are taught and some guides advocate that sentences should not start with certain conjunctions such as "and", "but", "because", and "so", authorities such as the Chicago Manual of Style state that this teaching has "no historical or grammatical foundation". Several other style guides either agree with the Chicago position or simply don't mention the controversy. Some writers advocate replacing an initial "But" with "However".
Many sources that assert there is no rule against starting a sentence with a conjunction advise that it should be used sparingly (for emphasis) and that creating a compound sentence out of two simple sentences is often preferable.  Some accept the practice in informal writing but not formal.
Some hypothesize that teachers invented the rule to encourage students to avoid overly simple sentences.
Catherine Soanes points out that coordinating conjuctions like "and" and "but" are least often allowed, some objections over the subordinating conjunction "because", but no complaint over subordinating conjunctions like "if".
- Cohesion (linguistics)
- Conjunctive adverb
- Conjunctive mood, sometimes used with conjunctions
- Logical conjunction
- On a white bus
- Serial comma - the comma used immediately before a coordinating conjunction preceding the final item in a list of three or more items
- Greenblatt, Stephen (2006). The Norton Anthology of British Literature, 8th Ed. Vol. D. New York: Norton. p. 478.
- Paul; Adams, Michael (2009). How English Works: A Linguistic Introduction (2nd ed.). New York: Pearson Longman. p. 152. ISBN 978-0-205-60550-7.
- Algeo, John (2006). British or American English? A Handbook of Word and Grammar Patterns. Cambridge Univ. Press.
- Burchfield, R. W., ed. (1996). Fowler's Modern English Usage (3rd ed.).
- Dryer, Matthew S. (2005). "Order of adverbial subordinator and clause". In Haspelmath, Martin; Dryer, Matthew S.; Gil, David; Comrie, Bernard. The World Atlas of Language Structures. Oxford University Press. ISBN 0-199-25591-1.
- University of Chicago (2010). The Chicago Manual of Style (16th ed.). Chicago: Univ. of Chicago Press. p. 257. ISBN 978-0-226-10420-1.
- "There is a persistent belief that it is improper to begin a sentence with And, but this prohibition has been cheerfully ignored by standard authors from Anglo-Saxon times onwards. An initial And is a useful aid to writers as the narrative continues." Quoted at: http://grammar.ccc.commnet.edu/Grammar/conjunctions.htm
- Wikitionary lists of conjuctions by language
- Difference between conjunctions, relative pronouns and relative adverbs, by Jennifer Frost