[sing.] a person who is sometimes very pleasant (Jekyll) and sometimes very unpleasant (Hyde) or who leads two very separate lives:
He leads an almost Jekyll and Hyde existence-by day he's an accountant, by night he's a singer in a rock band.
ORIGIN From the story by Robert Louis Stevenson, Dr Jekyll and Mr Hyde, in which Dr Jekyll takes a drug which separates the good and bad sides of his personality into two characters. All the negative aspects go into the character of Mr Hyde.
