A grammatical category is a unit of grammar based on a morphological opposition of grammatical meanings presented in grammatical forms.
The most general meanings rendered by language and expressed by systemic correlations of word-forms are interpreted in linguistics as grammatical meanings. Grammatical meanings ranged in oppositions and presented in grammatical forms build grammatical categories.
Grammatical forms can be morphemes, synthetic forms, and grammatical word combinations, which are analytical forms. Synthetic forms unite both lexical and grammatical meanings in one word. In analytical forms there two or more words in which at least one element is an auxiliary.