Sprain \Sprain\, v. t. [imp. & p. p. {Sprained}; p. pr. & vb. n. {Spraining}.] [OF. espreindreto press, to force out, F. ['e]preindre, fr. L. exprimere. See {Express}, v. t., and cf. {Spraints}.] To weaken, as a joint, ligament, or muscle, by sudden and excessive exertion, as by wrenching; to overstrain, or stretch injuriously, but without luxation; as, to sprain one's ankle.