frightening Get Printable Handwriting Rhymes Learn It! Spelling Test Definition verb. to cause fear in; scare Example Sentence A thunderstorm can be frightening. Synonyms scare; alarm; terrify; shock Antonyms cheer; reassure Rhymes Two Syllable Rhymes (6) brightening frightening heightening lightning tightening whitening Three Syllable Rhymes (7) brightening frightening heightening lightening tightening whitening enlightening Four Syllable Rhymes (1) enlightening Share with your friends: