from The American Heritage® Dictionary of the English Language, 4th Edition
- adv. Informal In a direct manner; bluntly: told me the truth flat out.
- adv. Informal At top speed: running flat out.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Used other than as an idiom: see flat, out.
- adj. Complete, total, downright.
- adj. Very busy.
- adj. Lazy, sleeping.
- adv. At top speed.
- adv. Bluntly, no holds barred, totally, outright.
- v. To fail after a promising beginning; to disappoint expectations.
Sorry, no etymologies found.