categorical adj.

1580s, in Aristotle's logic, "a highest notion," from French catégorie, from Late Latin categoria, from Greek katēgoria "accusation, prediction, category," verbal noun from katēgorein "speak against; to accuse, assert, predicate," from kata "down to" (or perhaps "against;" see cata-) + agoreuein "to harangue, to declaim (in the assembly)," from agora "public assembly" (from PIE root *ger- "to gather").

The Greek verb's original sense of "accuse" had weakened to "assert, name" by the time Aristotle applied katēgoria to his 10 classes of "expressions that are in no way composite," perhaps "things that can be named simply." Precisely what he meant by it "has been disputed almost from his own day till the present" [OED].

What, exactly, is meant by the word "category," whether in Aristotle or in Kant and Hegel, I must confess that I have never been able to understand. I do not myself believe that the term "category" is in any way useful in philosophy, as representing any clear idea. [Bertrand Russell, "A History of Western Philosophy," 1945]

The sense of "any very wide and distinctive class, any comprehensive of persons or things" is from 1660s.

category should be used by no-one who is not prepared to state (1) that he does not mean class, & (2) that he knows the difference between the two .... [Fowler]