belittle

Synonyms: bad-mouth blister criticize cut down to size cut to the quick decry deprecate depreciate deride derogate diminish discount discredit disparage dispraise downgrade downplay dump on knock lower minimize pan pooh pooh poor mouth put down rip roast run down scoff at scorch scorn shoot down shoot full of holes slam smear sneer at sour grapes squash squelch take a swipe at take down take down a peg tear down underestimate underrate undervalue write off

Antonyms: build up exaggerate praise value