nonchalant
/ˈnɒnʃ(ə)l(ə)nt
/adjective
(Of a person or manner) feeling or appearing casually calm and relaxed; not displaying anxiety, interest, or enthusiasm: she gave a nonchalant shrug...
- Doc Charlie would casually flirt with the nonchalant female who would ever so calmly refuse.
- He'd said it in such an offhand and nonchalant manner, though, that I decided to let it drop.
- He was very nonchalant, very offhand at the press conference when he was making those comments.
Origin
Mid 18th century: from French, literally 'not being concerned', from the verb nonchaloir.
This is an English use of a French word meaning literally ‘not being concerned’, from the verb nonchaloir; the chaloir element is from Latin calere ‘be warm, be roused with zeal’.