insouciant - Definitions from Dictionary.com (etymology):

insouciant (in-SOO-see-uhnt) adjective

Marked by blithe unconcern; nonchalant.

The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2000 by Houghton Mifflin Company.
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adj : marked by blithe unconcern; "an ability to interest casual students"; "showed a casual disregard for cold weather"; "an utterly insouciant financial policy"; "an elegantly insouciant manner"; "drove his car with nonchalant abandon"; "was polite in a teasing nonchalant manner" [syn: casual, nonchalant]

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