mildew Get Printable Handwriting (mil-dew) 2 syllables Rhymes Learn It! Spelling Test Definition noun. any of various fungi that form a superficial usually whitish growth on plants and various organic materials; a plant disease caused by such fungi Example Sentence The tub had mildew around the drain. Synonyms mold; fungus; moldy; plant disease Antonyms healthy plant; mold free Rhymes Two Syllable Rhymes (1) mildew Share with your friends: