Disappoint
late Middle English (in the sense ‘deprive of a position’): from Old French desappointer .
wiktionary
From Middle French desapointer (compare French désappointer).
(This etymology is missing or incomplete. Please add to it, or discuss it at the Etymology scriptorium. Particularly: “Whence the adjective?”)
etymonline
disappoint (v.)
mid-15c., disappointen, "dispossess of appointed office," from dis- "reverse, opposite of" + appoint, or else from Old French desapointer "undo the appointment, remove from office" (14c., Modern French from désappointer). Modern sense of "to frustrate the expectations or desires of" is from late 15c. of persons; of plans, etc., "defeat the realization or fulfillment of," from 1570s, perhaps via a secondary meaning of "fail to keep an appointment."
