"so they is negroes?"

wikipedia:

The term conjugation is applied only to the inflection of verbs, and not of other parts of speech (inflection of nouns and adjectives is known as declension). Also it is often restricted to denoting the formation of finite forms of a verb – these may be referred to as conjugated forms, as opposed to non-finite forms, such as the infinitive or gerund, which tend not to be marked for most of the grammatical categories