from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Lacking a sense of responsibility; reckless.
- adv. With abandon; recklessly.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. wild, careless, irresponsible
- adv. wildly, carelessly, irresponsibly
from the GNU version of the Collaborative International Dictionary of English
- adj. Wild; giddy; flighty; rash; thoughtless.
from The Century Dictionary and Cyclopedia
- Harebrained; flighty; giddy; rash.
- n. A giddy, harebrained, or rash person.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a reckless impetuous irresponsible person
- adv. in a wild or reckless manner
- adj. cheerfully irresponsible
Perhaps alteration of hare 'em, scare 'em : hare, to frighten + scare.(American Heritage® Dictionary of the English Language, Fourth Edition)