antonymous 1

(of words) meaning the same or nearly the same

a word that expresses a meaning opposed to the meaning of another word, in which case the two words are antonyms of each other

of words or propositions so related that each is the negation of the other

of words or propositions so related that both cannot be true and both cannot be false

of words or propositions so related that both cannot be true but both may be false

of words so related that one contrasts with the other

of words so related that one reverses the relation denoted by the other