humble adjective Definition: not acting superior Synonyms: shy, down-to-earth, modest, low in rank Antonyms: aggressive, confident, boastful In which sentence would the word "humble” best be replaced by the word "modest”? Humble Pluto was once considered a planet, but is now only a dwarf planet. The humble child sat by herself in the corner of the room. The experience will surely humble most individuals. His humble attitude made it easy for everyone to like him.