to disdain; to look down on; to make light of; to hold in contempt; to scorn; to despise
相手を侮った選手は負けた。
The player who underestimated his opponent lost.
敵を侮っては、痛い目を見るぞ。
If you underestimate the enemy, you'll regret it.
どんな小さな仕事でも侮るべきではない。
You should never underestimate even the smallest task.