[v] lower the grade of something; reduce its worth
degrade
adulterate, alloy, bargain, beat down, bid, bid for, break, canker, chaffer, coarsen, confound, contaminate, corrupt, cut, cut prices, debase, debauch, decline, decry, defile, deflate, deflower, degenerate, degrade, denature, deprave, depreciate, desecrat