disappointing (adj.)

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."