discomfit (v.) Look up discomfit at Dictionary.com
c. 1200, as an adjective, from Old French desconfit "vanquished, defeated," past participle of desconfire "to defeat, destroy," from des- "not" (see dis-) + confire "make, prepare, accomplish," from Latin conficere "to prepare," from com- "with" (see com-) + combining form of facere "to make, to do" (from PIE root *dhe- "to set, put").

Used as a verb in English from c. 1300. Weaker sense of "disconcert" is first recorded 1520s in English, probably by confusion with discomfort. Related: Discomfited; discomfiting.