define nonchalance
nonchalance meaning, nonchalance definition | English Cobuild dictionary. 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. â¦ nonchalance n-uncount. Affecting nonchalance, I handed her two hundred dollar bills.