FUNCTION WORD

A. DEFINITION OF FUNCTION WORD
There are many definition of funtion words such as :
> Function word are a word, such as a preposition, a conjunction, or an article, that has little semantic content of its own and chiefly indicates a grammatical relationship. It also called form word or functor.
> Function word are word that expresses grammatical relationships and has little semantic content it is also a word that serves a grammatical function but has no identifiable meaning ( Synonym: closed-class word).
So we can conclude that :
Function words (or grammatical words or synsemantic words or structure-class words) are words that have little lexical meaning or have ambiguous meaning, but instead serve to express grammatical relationships with other words within a sentence, or specify the attitude or mood of the speaker. They signal the structural relationships that words have to one another and are the glue that holds sentences together. Thus, they serve as important elements to the structures of sentences.
Words that are not function words are called content words (or open class words or lexical words or autosemantic words): these include nouns, verbs, adjectives, and most adverbs, although some adverbs are function words (e.g., then and why). Dictionaries define the specific meanings of content words, but can only describe the general usages of function words. By contrast, grammars describe the use of function words in detail, but treat lexical words in general terms only.
B. CLASSIFICATION OF FUNCTION WORD
Function words might be prepositions, pronouns, auxiliary verbs, conjunctions, grammatical articles or particles, all of which belong to the group of closed-class words. Interjections are sometimes considered function words but they belong to the group of open-class words. Function words might or might not be inflected or might have affixes.
Function words belong to the closed class of words in grammar in that it is very uncommon to have new function words created in the course of speech, whereas in the open class of words (that is, nouns, verbs, adjectives, or adverbs) new words may be added readily (such as slang words, technical terms, and adoptions and adaptations of foreign words).
Each function word either gives some grammatical information on other words in a sentence or clause, and cannot be isolated from other words, or it may indicate the speaker's mental model as to what is being said.
Grammatical words, as a class, can have distinct phonological properties from content words. Grammatical words sometimes do not make full use of all the sounds in a language.
For example in English, only function words begin with voiced th- .
The following is a list of the kind of words considered to be function words:
1. Articles — the, and a, an. In some inflected languages, the articles may take on the case of the declension of the following noun.
 The is used when the noun which follows name an identified specimen, that is when it is believed that the hearer knows which person, places or thing the noun refers to.
 a is used when an inidentified specimen is introduce, it is used when the beginning of a word is consonant
 an is used when the beginning of a word is vowel ( a, i, u, e, o )
2. Pronouns — pronoun refers to a anoun. It is used in places of a noun.It is inflected in English, as :
 I – me
 You --- you
 we --- us
 they --- them
 he — him
 she — her
 it --- it
3. Adpositions — uninflected in English
4. Conjunctions — is a part of speech that connects two words, sentences, phrases or clauses together. This definition may overlap with that of other parts of speech, so what constitutes a "conjunction" should 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.
 Coordinating conjuntion.
The definition can also be extended to idiomatic phrases that behave as a unit with the same function as a single-word conjunction (as well as, provided that, etc.). Coordinating conjunctions, also called coordinators, are conjunctions that join two or more items of equal syntactic importance, such as words, main clauses, or it’s 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 "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" ("Can we perform? Only if we practice").
Here are the meanings and some examples of coordinating conjunctions in English:
• for: presents a reason ("He is gambling with his health, for he has been smoking far too long.") (though "for" is more commonly used as a preposition)
• and: presents non-contrasting item(s) or idea(s) ("They gamble, and they smoke.")
• nor: presents a non-contrasting negative idea ("They don't gamble, nor do they smoke.")
• but: presents a contrast or exception ("They gamble, but they don't smoke.")
• or: presents an alternate item or idea ("Every day they gamble, or they smoke.")
• yet: presents a contrast or exception ("They gamble, yet they don't smoke.")
• so: presents a consequence ("He gambled well last night, so he smoked a cigar to celebrate.")
 Correlative conjunctions
: are pairs of conjunctions that work together to coordinate two items. English examples include both…and, [n]either…[n]or, and not [only]…but [also], whether... or.
Examples:
• 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 go is your decision.
 Subordinating conjunctions, also called subordinators, are conjunctions that introduce a dependent clause.
The most common subordinating conjunctions in the English language include the following: after, although, as if, as much as, as long as, as soon as, as though, because, before, even if, even though, if, in that, in order that, lest, since, so that, than, that, though, unless, until, when, whenever, where, wherever, whether, 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, while), when used to introduce a phrase instead of a full clause, become prepositions with identical meanings.
5. Auxiliary verbs — forming part of the conjugation (pattern of the tenses of main verbs), always inflected.
Present : is, am, are
Past : was, were
6. Interjections —Interjections are sometimes considered function words but they belong to the group of open-class words, sometimes called “filled pauses”, it is uninflected.
7. Particles — convey the attitude of the speaker and are uninflected, as if, then, well, however, thus, etc.
8. Expletives — take the place of sentences, among other functions as It, it can represent time, day, weather/season, situation.
Example : I have just bought a book entitle “How to Read a Thousand Word a Minute” . Perhaps it will solve my problem, but i just haven’t hadtime to read it.
9. Pro-sentences — yes, okay, etc.