impugn

Synonyms: assail attack blast break call into question cast aspersions upon cast doubt upon come down on contradict contravene cross cut to shreds deny disaffirm dispute gainsay knock negate negative oppose pin something on put down question resist run down skin alive slam smear stick it to swipe at tar throw doubt on throw the book at thumb nose at traduce trash traverse zap zing

Antonyms: flatter praise