to make weak or weaker.

Phonetics . to change (a speech sound) to an articulation requiring less effort, as from geminate to nongeminate or from stop to fricative.

to become weak or weaker.

verb

build up , strengthen

verb

abate , adulterate , break up , cripple , crumble , cut , debase , debilitate , decline , decrease , depress , devitalize , dilute , diminish , droop , dwindle , ease up , enervate , exhaust , fade , fail , faint , flag , give way , halt , impair , impoverish , invalidate , languish , lessen , limp , lose , lose spirit , lower , minimize , mitigate , moderate , reduce , relapse , relax , sap , slow down , soften , temper , thin , thin out , tire , totter , tremble , undermine , vitiate , wane , water down , wilt , degenerate , deteriorate , sink , waste , attenuate , enfeeble , undo , unnerve , water , ease off , relent , slacken , yield , damage , defeat , deplete , disable , emasculate , extenuate , incapacitate , paralyze , sag , stultify , unman