from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Blithe lack of concern; nonchalance.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. carelessness, heedlessness, indifference, or casual unconcern
- n. nonchalance
from the GNU version of the Collaborative International Dictionary of English
- n. Carelessness; heedlessness; thoughtlessness; unconcern.
from The Century Dictionary and Cyclopedia
- n. The quality of being insouciant; heedless indifference or unconcern; carelessness of feeling or manner.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. the cheerful feeling you have when nothing is troubling you
From French insouciance, from in- ("not") + souciant ("worrying"). (Wiktionary)