Grade 7 water vapor Get Printable Handwriting Hear It! Say It! Write It! Learn It! Spelling Test Definition noun. the gaseous form of water in the air. Example Sentence One state of the water cycle is water vapor. More Example Sentences Water vapor is important for weather patterns. Synonyms steam; humidity; moisture Antonyms ice Hear It! Say It! Write It! water vapor Switch to cursive Start Share with your friends: