cool, casual, calm, easy, unemotional, neutral
annoying
The man was nonchalant
irresponsible, sloppy, cavalier, offhand, neglectful, lackadaisical, negligent, thoughtless, absent-minded, nonchalant, slapdash
Nonchalant was born on 1970-10-18.
Nonchalant, he lifted her skirt, (which was hanging on the clothesline).
The noun is nonchalance.
Example sentence - He acted quite nonchalant about the evening with her.
You could say: Nathan's heart was beating loudly and feared his girlfriend would hear it, however he continued to act nonchalant.
Not necessarily but a nonchalant attitude can be viewed as noncaring or detached.
nonchalant, nondistictive, and nondurable.
I couldn't understand how she could be so nonchalant about a job interview with such a prestigious law firm.
If you are nonchalant instead of remorseful, the judge will give you a very strict prison sentence.