nonchalance
nounUK /ˈnɒnʃələns/
US /ˌnɑːnʃəˈlɑːns/
A calm way of acting like nothing is a big deal.
She waved goodbye with a cool nonchalance, as if the whole trip had been nothing.
RELATED WORDS
OTHER MEANINGS
2. A relaxed and easy manner that makes other people feel at ease.
His nonchalance about the mistake helped everyone stay calm.
3. A lack of worry or interest that can seem careless.
The teacher frowned at the nonchalance with which he lost his homework.
4. The quality of seeming not to care about things that matter to others.
Her nonchalance about the broken vase surprised her brother.