1. to weaken, damage, or gradually destroy someone's confidence or conviction about something
Recent discoveries undermine certainty about the ancient civilization's origins.
Descobertas recentes minam a certeza sobre as origens da civilização antiga.
2. to cast doubt upon or reduce the reliability of established beliefs or facts
The witness's testimony was designed to undermine certainty in the defendant's guilt.
O testemunho da testemunha foi projetado para minar a certeza da culpa do réu.