Category

Any class or system of grammatical or lexical units distinguished at some level in the structure of a language. ‘Noun phrase’, for example, is a syntactic category.
‘Case’ and ‘tense’ are inflectional or morphosyntactic categories. Colour terms or terms for kinship might be said to form a ‘lexical category’, and so on.

Any class or system of grammatical or lexical units distinguished at some level in the structure of a language. ‘Noun phrase’, for example, is a syntactic category.
‘Case’ and ‘tense’ are inflectional or morphosyntactic categories. Colour terms or terms for kinship might be said to form a ‘lexical category’, and so on.

The definition of a category is actually similar to that of a phoneme; phonemes were defined to be substitution classes up to meaning preservation. Here we define the classes up to grammaticality (more or less, since we have the caveat about ‘constituent occurrences’ because we are dealing with the substitution of strings for strings, not just of an item for another item)

Sources:

The Concise Oxford Dictionary of Linguistics P. H. Matthews

https://linguistics.ucla.edu/people/Kracht/courses/ling20-fall07/ling-intro.pdf