: harmful often in a subtle or unexpected way
Marguerite is convinced that violent television programs will have a deleterious effect on her children, so she carefully monitors what they watch.
"Democrats and Republicans, because of their nefarious relationships with lobbyists, have turned a blind eye to the deleterious consequences of government and tax policy that is determined by special interests." -- From an opinion column by LeRoy Goldman in The Asheville Citizen-Times (North Carolina), January 27, 2011
Did You Know?
"Pernicious," "baneful," "noxious," and "detrimental" are the wicked synonyms of "deleterious." All five words refer to something exceedingly harmful. Of the group, "deleterious" is most often used for something that is unexpectedly harmful. "Pernicious" implies irreparable harm done by something that corrupts or undermines in an evil or insidious way ("the assertion that hateful speech has a pernicious effect on society"), while "baneful" suggests injury through poisoning or destruction ("the baneful notion that discipline destroys creativity"). "Noxious" can apply to anything that is both offensive and injurious to the health of body or mind ("noxious chemical fumes"), while "detrimental" implies an obvious harmfulness to something specified ("the detrimental effects of excessive drinking").
Test Your Vocabulary with M-W Quizzes
Name That Synonym
Fill in the blanks to create another word meaning "harmful": nco_s. The answer is ...