late 14c., misusen, "use or treat improperly;" from mis- (1) "badly, wrongly" + use (v.) and in part from Old French mesuser (Modern French méuser), from mis- (2). Meaning "abuse, treat badly, subject to ill-treatment" is attested from 1530s. Related: Misused; misusing; misusage.
late 14c., "improper use, misapplication," from mis- (1) "bad, wrong" + use (n.) and in part from Old French mesus "abuse, excess, misdeed." As "abuse, ill-treatment" it is attested from 1590s.