Webster's Revised Unabridged Dictionary · 1913

Harum-scarum

Harum-scarum (hâr"um*skâr"um) , adjective

[Compare hare,transitive verb, and scare, transitive verb]

Wild; giddy; flighty; rash; thoughtless. [Colloquial]
They had a quarrel with Sir Thomas Newcome's own son, a harum-scarum lad. — Thackeray