Traditionally, grammar has been divided into syntax and morphology, syntax dealing with the relations between words in sentence structure and morphology with the internal grammatical structure of words. The relation between girl and girls and the relationship (irregular) between woman and women would be part of morphology; the relation of concord between the girl [or woman] is here and the girls [or women] are here would be part of syntax. It must, however, be emphasized that the distinction between the two is not as clear-cut as this brief illustration might suggest. This is a matter for debate between linguists of different persuasions; some would deny the relevance of distinguishing morphology from syntax at all, referring to grammatical structure as a whole under the term syntax.
Grammar is different from phonology and vocabulary (see below Semantics), though the word grammar is often used comprehensively to cover all aspects of language structure. Categories such as plural, past tense, and genitive case are not phonological categories. In spoken language they are, like everything else, expressed in speech sounds, but within a language these may be very different for one and the same category. In English noun plurals, the added -s in cats, the vowel changes in man, men and in goose, geese, and the -en in oxen are quite different phonologically; so are the past-tense formatives such as -ed in guarded, -t in burnt, vowel change in take, took, and vowel and consonant change in bring, brought. In Latin the genitive case can be represented in singular nouns by -ī, -is, -ae, -ūs, and -eī. The phonological difference does not matter, provided only that the category distinction is somehow expressed.
The same is true of the orthographic representation of grammatical differences, and the examples just given illustrate both cases. This is why the grammar of written language can be dealt with separately. In the case of dead languages, known with certainty only in their written forms, this must necessarily be done; insofar as the somewhat different grammar of their spoken forms made use of sound features not represented in writing (e.g., stress differences), this can, at best, only be inferred or reconstructed.
Grammatical forms and grammatical structures are part of the communicative apparatus of languages, and along with vocabulary, or lexicon (the stock of individual words in a language), they serve to express all the meanings required. Spoken language has, in addition, resources such as emphatic stressing and intonation. This is not to say, however, that grammatical categories can be everywhere directly related to specific meanings. Plural and past tense are fairly clear as regards meaning in English, but even here there are difficulties; in if I knew his address, I would tell you, the past-tense form knew refers not to the past but to an unfulfilled condition in the present. In some other languages greater problems arise. The gender distinctions of French, German, and Latin are very much part of the grammar of these languages, but only in a small number of words do masculine, feminine, and neuter genders correspond with differences of sex, or with any other category of meaning in relation to the external world. Semantics
Language exists to be meaningful; the study of meaning, both in general theoretical terms and in reference to a specific language, is known as semantics. Semantics embraces the meaningful functions of phonological features, such as intonation, and of grammatical structures and the meanings of individual words. It is this last domain, the lexicon, that forms much of the subject matter of semantics. The word stock of a language is very large; The Oxford English Dictionary, for example, consists of some 600,000 words. When the lexicons of specialized, dialectal, and global varieties of English are taken into account, this total must easily exceed one million. The lexicons of less widely used languages can be just as large.
Among the many examples of investigation for study within semantics are the sense relations between words (such as synonymy and antonymy), the nature of “semantic features” of word meaning (e.g., woman = [adult, female, human]), and the ways in which words group themselves into domains (“semantic fields”). Once again, it must be stressed that questions arising from the relations between semantics, grammar, and phonology are the subjects of continuing controversy. Language variants
The word language contains a multiplicity of different designations. Two senses have already been distinguished: language as a universal species-specific capability of the human race and languages as the various manifestations of that capability, as with English, French, Latin, Swahili, Malay, and so on. There is, of course, no observable universal language over and above the various languages that have been or are spoken or written, but one may choose to concentrate on the general and even the universal features, characteristics, and components of different languages and on the ways in which the same sets of descriptive procedures and explanatory theories may be applied to different languages. In so doing one may refer to language (in general) as one’s object of study. This is what is done by linguists, or linguistic scientists, persons devoting themselves to the scientific study of languages (as opposed to the popular sense of linguists as polyglots, persons having a command of several different languages). Dialects
It has already been pointed out that no two persons speak exactly alike, and, within the area of all but the smallest speech communities (groups of people speaking the same language), there are subdivisions of recognizably different types of language, called dialects, that do not, however, render intercommunication impossible or markedly difficult. Because intercomprehensibility lies along a scale, the degree required for two or more forms of speech to qualify as dialects of a single language, instead of being regarded as separate languages, is not easy to quantify or to lay down in advance, and the actual cutoff point must in the last resort be arbitrary. In practice, however, the terms dialect and language can be used with reasonable agreement. One speaks of different dialects of English (Southern British English, Northern British English, Scottish English, Midwest American English, New England American English, Australian English, and so on, with, of course, many more delicately distinguished subdialects within these very general categories), but no one would speak of Welsh and English or of Irish and English as dialects of a single language, although they are spoken within the same areas and often by people living in the same villages as each other. Jargon
Sometimes, as in the case of criminal argots, part of the function of special languages is deliberately to mislead and obstruct the rest of society and the authorities in particular; they may even become wholly impenetrable to outsiders. But this is not the sole or main purpose of most specialized varieties of language. Professions whose members value their standing in society and are eager to render their services to the public foster their own vocabulary and usage, partly to enhance the dignity of their profession and the skills they represent but partly also to increase their efficiency. An example of this is the language of the law and of lawyers.