plumps Get Printable Handwriting Hear It! Say It! Write It! Learn It! Spelling Test Definition verb. to become fuller, rounder, or thicker. Example Sentence She plumps up the pillows on the couch every morning. Synonyms swells; fattens; bulks up Antonyms shrinks; deflates Hear It! Say It! Write It! plumps Switch to cursive Start Share with your friends: