Meaning

adjective with little or no preparation or forethought

adjective casually thoughtless or inconsiderate

adverb without previous thought or preparation

originFrom Middle English *ofhande, *ofhende, from Old English ofhende (“absent, lost”), ultimately from Proto-Germanic *abahandijaz. Equivalent to (and re-formed as) off- + hand. Cognate with Icelandic afhendur. Compare onhand.

Etymology from Wiktionary, CC BY-SA 3.0