n. In rhet.: A figure by which a word is used to designate an object, idea, or act to which it can be applied only by an exceptional or undue extension of its proper sphere of meaning: as, to stone (pelt) a person with bricks; a palatable tone; to display one's horsemanship in riding a mule; to drink from a horn of ivory.n. In philology, the employment of a word under a false form through misapprehension in regard to its origin: thus, causeway and crawfish or crayfish have their forms by catachresis.