Main units of Grammar are a word and a sentence. A word may be divided into morphemes; a sentence may be divided into phrases (word-groups). A morpheme, a word, a phrase and a sentence are units of different levels of language structure. A unit of a higher level consists of one or more units of a lower level.
Grammatical units - 2 types of relations:
- in the language system (paradigmatic relations)
- in speech (syntagmatic relations).
In the language system each unit is included into a set of connections based on different properties. F. ex., word forms child, children, child's, children's have the same lexical meaning and have different grammatical meanings. They constitute a lexeme.
Word-forms children, boys, men, books... have the same grammatical meaning and have different lexical meanings. They constitute a gram meme (a categorical form, a form class). The system of all gram memes (grammatical forms) of all lexemes (words) of a given class constitutes a paradigm.
Syntagmatic relations are the relations in an utterance.
Main grammatical units, a word and a sentence, are studied by different sections of Grammar: Morphology (Accidence) and Syntax. Morphology studies the structure, forms and the classification of words. Syntax studies the structure, forms and the classification of sentences. Morphology studies paradigmatic relations of words, Syntax studies syntagmatic relations of words and paradigmatic relations of sentences.
There is also a new approach to the division of Grammar into Morphology and Syntax. According to this approach Morphology should study both paradigmatic and syntagmatic relations of words. Syntax should study both paradigmatic and syntagmatic relations of sentences. Syntactic syntagmatics is a relatively new field of study, reflecting the discourse.