The verb 'sprain' entered English in the early 17th century, derived from the Middle French verb 'espraindre' meaning 'to press out, to wrench'. This French term likely evolved from the Latin 'exprimere' (to press out, force out), composed of 'ex-' (out) and 'premere' (to press). The semantic journey reflects a shift from the general act of pressing or squeezing to the specific physical trauma of wrenching a joint. The '-ed' participle form naturally extended to function as an adjective describing the resulting injured state, a common grammatical process in English.

The word 'sprain' is a simplex verb of uncertain, likely French origin. The '-ed' suffix is a productive inflectional morpheme from Old English, used to form the past tense and past participle of regular verbs, which here also functions as an adjective.