—adj. 1. no longer in general use; fallen into disuse: an obsolete expression. 2. of a discarded or outmoded type; out of date: an obsolete battleship. 3. (of a linguistic form) no longer in use, esp., out of use for at least the past century. Cf. archaic. 4. effaced by wearing down or away.
5. Biol.imperfectly developed or rudimentary in comparison with the corresponding character in other individuals, as of the opposite sex or of a related species.
—v.t. to make obsolete by replacing with something newer or better; antiquate: Automation has obsoleted many factory workers.