grammar, description of the structure of a language, consisting of the sounds (see phonology); the meaningful combinations of these sounds into words or parts of words, called morphemes; and the arrangement of the morphemes into phrases and sentences, called syntax. School grammars for the speakers of a standard language (e.g., English grammars for English-speaking students) are not descriptive but prescriptive, that is, they are rule books of what is considered correct. Such grammars have popularized many unsound notions because they often fail to take into account common usage and they do not differentiate language styles and levels, such as formal or colloquial; standard, nonstandard, or substandard; or dialect differences.
Morphemes may have lexical meaning, as the word bird, or syntactic meaning, as the plural –s (see inflection; etymology). Words are minimal free forms, but a word may contain more than one morpheme. For example, treatment contains two, treat and the derivational noun-forming suffix -ment. In traditional grammar, parts of speech are defined semantically, i.e., a noun is a person, place, or thing; but in linguistic morphology, parts of speech are defined according to their syntactic function: The difference between nouns and verbs is that they cannot appear in the same environment in a sentence. One method of language classification is based on structure; languages are classified according to the degree of synthesis, or the number of morphemes per word. Analytic languages, such as Chinese, have only one morpheme per word, while in synthetic languages one word represents more than one morpheme; in the case of some Native American languages, a single word may have so many morphemes that it is the equivalent of an English sentence. The list of morphemes and their meanings (see semantics) in a language is usually not part of a grammar but is isolated in a dictionary or vocabulary.
In syntax, units larger than morphemes, such as phrases and sentences, are isolated in manner that reflects a hierarchical structure; thus the sentence "My sister Mary slowly took the cake from the shelf" would have as primary constitutents "My sister Mary" and "slowly took the cake from the shelf." Each primary constituent then may be broken down into a series of hierarchical secondary constituents. The analysis of syntax is also concerned with the ordering of the grammatical sequences within the phrase, with agreement between concomitant entities (i.e., agreement of number and gender between subject and verb, noun and pronoun), and with case, as mandated by the position and function of a word within a sentence. Other aspects of syntax include such sentence transformations as negativization, interrogation, coordination, subordination, passivization and relativization.
The first attempts to study grammar began in about the 4th cent. BC, in India with Panini's grammar of Sanskrit and in Greece with Plato's dialogue Cratylus. The Greeks, and later the Romans, approached the study of grammar through philosophy. Concerned only with the study of their own language and not with foreign languages, early Greek and Latin grammars were devoted primarily to defining the parts of speech. The biblical commentator Rashi attempted to decipher the rules of ancient Hebrew grammar. It was not until the Middle Ages that grammarians became interested in languages other than their own. The scientific grammatical analysis of language began in the 19th cent. with the realization that languages have a history; this led to attempts at the genealogical classification of languages through comparative linguistics. Grammatical analysis was further developed in the 20th cent. and was greatly advanced by the theories of structural linguistics and transformational-generative grammar (see linguistics).
See N. Chomsky, Aspects of the Theory of Syntax (1965) and Knowledge of Language: Its Nature, Origin and Use (1986); R. W. Langacker, Language and Its Structure (2d ed. 1973); F. J. Newmeyer, Grammatical Theory (1983); V. C. Cook, Chomsky's Universal Grammar (1988).