adjective
- reckless; rash; irresponsible: He had a harum-scarum youth.
- disorganized; uncontrolled.
adverb
- recklessly; wildly: He ran harum-scarum all over the place.
noun
- a reckless person.
- reckless or unpredictable behavior or action.
adjective, adverb
- in a reckless way or of a reckless nature
noun
- a person who is impetuous or rash
1670s (adv.), probably a compound of obsolete hare (v.) “harry” + scare (v.), with ‘um as a reduced form of them. As an adjective from 1751; as a noun from 1784.