Categories and linguistic levels

A category, in general, defines a class of similar things. In principle, therefore, a linguistic category defines a class of linguistic objects, such as verbs, which are related in terms of paradigmatic relations, as already defined.

This very general definition of a category applies to a wide variety of specific categories:

1. A phonological category covers a class of phonologically similar words, such as monosyllable, accented word, for example.
2. A morphological category covers an inflexional paradigm class, i.e. a class of words with similar inflexional paradigms, such as related irregular verbs (swim, swam, swum with sing, sang, sung; it might or a derivational class, i.e. a class of words with similar stems and derivational affixes, such as notable, affordable, faxable, doable; it might be a class of compound words, such as red-head, blackleg or steel factory, cake shop.
3. A morpho-syntactic category covers a category which links inflexions to syntactic categories, e.g. PERSON, GENDER, NUMBER, TENSE, ASPECT, VOICE.
4. A syntactic category (more precisely: a sentence-syntactic category) covers words which occur in similar syntactic contexts; traditionally these cover NOUN, ADJECTIVE, ARTICLE, PRONOUN, VERB, ADVERB, PREPOSITION, CONJUNCTION, INTERJECTION. A syntactic category is also known as a word class or as a part of speech, pars orationis.
5. A semantic category covers a class of words similar in respect of meaning, for instance the class of ANIMATE, HUMAN, MALE nouns.
6. A pragmatic category covers a class of words with similar relations to speakers and hearers involved in the use of words (where pragmatic categories are relevant, I will treat pragmatic properties as a more general kind of semantic property, i.e. as another aspect of meaning).