- Je·kyll and Hyde
- /ˈʤɛkələnˈhaıd/ noun [singular]: someone who is sometimes good and pleasant and sometimes very rude or bad
He's a real Jekyll and Hyde who can become violent without warning.
his Jekyll and Hyde tendencies
◇ This term comes from “The Strange Case of Dr. Jekyll and Mr. Hyde,” a story by Robert Louis Stevenson. In the story, Dr. Jekyll is a scientist who creates a liquid that changes him from a good man to the evil Mr. Hyde when he drinks it.
Useful english dictionary. 2012.