What is a term or word which is the opposite of, or antithesis to, another; an antonym; -- the opposite of synonym; as, "foe" is the counterterm of "friend". C. J. Smith called?

counterterm — A term or word which is the opposite of, or antithesis to, another; an antonym; -- the opposite of synonym; as, "foe" is the counterterm of "friend". C. J. Smith. (Webster's 1913.)

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