lullaby Get Printable Handwriting (lull-a-by) 3 syllables Rhymes Learn It! Spelling Test Definition noun. a song sung to put a child to sleep. Example Sentence The mother sang a lullaby to the baby. Synonyms soothing song; calm song; song for sleep Antonyms agitate; arouse; stir; waken Rhymes Three Syllable Rhymes (1) lullaby Share with your friends: