lunatic Get Printable Handwriting (lu-na-tic) 3 syllables Rhymes Learn It! Spelling Test Definition n and adjective. 1 someone who is insane; 2 someone who acts in a bizarre or wild manner. Example Sentence He is a lunatic. Synonyms crazy; mad; absurd Antonyms healthy; sane; sensible Rhymes Three Syllable Rhymes (1) lunatic Share with your friends: