NONCHALANTLY
casually, nonchalantly
(adverb) in an unconcerned manner; “glanced casually at the headlines”
coolly, nervelessly, nonchalantly
(adverb) in a composed and unconcerned manner; “without more ado Barker borrowed a knife from his brigade Major and honed it on a carborundum stone as coolly as a butcher”
Source: WordNet® 3.1
Etymology
Adverb
nonchalantly (comparative more nonchalantly, superlative most nonchalantly)
In a nonchalant manner.
Source: Wiktionary
Non"cha*lant`ly, adv.
Definition: In a nonchalant, indifferent, or careless manner; coolly.
NONCHALANT
Non`cha`lant", a. Etym: [F., fr. non not (L. non) + chaloir to
concern one's self for, fr. L. calere to be warm, to be inflamed with
desire, to be troubled. See Non-, and Caldron.]
Definition: Indifferent; careless; cool.
Source: Webster’s Unabridged Dictionary 1913 Edition