The word is the basic unit of language. The principle characteristics of the word are as follows:
1) The word is a unity of the external and the internal structure, i.e. a unity of form and content; thus, it is a two-facet unit.
By the external structure of the word we mean its sound form, morphemic composition, and derivational structure.
The internal (or semantic) structure of the word is all its meanings together.
2) The word is characterized both by external (formal) unity and internal unity.
Its external unity means that a word has a single grammatical meaning,
e.g. blackbird – blackbirds (pl). The first component black can't have any grammatical forms of its own, whereas in a word-group each constituent can have its own grammatical forms, e.g. the blackest birds I've ever seen.
Semantic (internal) unity means that each meaningful word conveys one concept,
a green house-greenhouse -теплица
3) The word is a cluster of forms and variants:
a) phonetic variants, e.g. schedule ['skedju:l],
b) morphological variants, e.g. dreamed/dreamt,
c) parallel formations of the type geographic/geographical;
(but compare historic - historical, which are separate words);
d) lexico-semantic variants, by which we mean one polysemantic word in its different meanings,
e.g. bird 1) a feathered living creature,2) (sl) young woman,3) (coll) person.
4) The word is capable of grammatical employment. In speech, it is used in one of its grammatical forms, which are the smallest units at syntactic level, in a certain function.
The word is a nominative language unit, an association of a particular meaning with a particular series of sounds, capable of grammatical employment.
There are several approaches to the study of the word.
1) atomistic approach, i.e. lexical units were studied as unconnected separate items.
2) The vocabulary is studied as a system (systemic approach), i.e. the word is studied in its relations to other words in the vocabulary as a component of various sets, groups, fields.
3) nominative approach. The nominative approach is concerned with how things get their names.
4) The functional approach studies how words are combined in speech, i.e. a word is observed, studied and described in its typical contexts,
5) The communicative approach studies how words are used for purposes of communication,
