The word "over-weening" is often used to describe someone who is excessively confident, arrogant, or conceited. Its antonyms would be words that describe the opposite of these qualities. Humble, modest, and unassuming are three antonyms for the word "over-weening". If someone is humble, they are not boastful or having an exaggerated sense of their own importance. Modest describes someone who is not excessively confident and is measured and reasonable when speaking about their abilities. Unassuming person is someone who doesn't put on airs, who doesn't pretend to be smarter or better than they are.