The word "un-presuming" means not having or showing excessive confidence or self-importance. Its antonyms can be words like arrogant, boastful, egotistical, overbearing, and pompous. These words suggest that someone who is un-presuming may be humble, modest, unassuming, or self-effacing, while their opposite traits reflect a sense of superiority, conceit, and overconfidence. In a nutshell, antonyms for un-presuming suggest that someone is overly confident, boastful, or arrogant, while synonyms suggest that someone is more modest, unassuming, and unpretentious in their attitude and behavior.