adjective coolly unconcerned, indifferent, or unexcited; casual: His nonchalant manner infuriated me.
Origin: 1725–35; <
French nonchalant, present participle of obsolete
nonchaloir to lack warmth (of heart), be indifferent, equivalent to
non- non- +
chaloir <
Latin calēre to be warm. See
-ant Related forms non·cha·lant·ly, adverb
Synonyms
cool, calm, collected, composed.
Antonyms
excitable.