nonchalant
If you describe someone as nonchalant, you mean that they appear not to worry or care about things and that they seem very calm. adj
(=casual)
Clark's mother is nonchalant about her role in her son's latest work..., It merely underlines our rather more nonchalant attitude to life.
♦
nonchalance n-uncount
Affecting nonchalance, I handed her two hundred dollar bills.
♦
nonchalantly adv usu ADV with v, also ADV adj
(=casually)
`Does Will intend to return with us?' Joanna asked as nonchalantly as she could.