flippant
adjective
UK/ˈflɪp.ᵊnt/
US/ˈflɪp.ᵊnt/
Definitions of flippant adjective
not showing a serious or respectful attitude towards a subject that should be taken seriously, often in an attempt to be humorous or clever
He answered the serious question with a flippant attitude.
Don't be flippant about this! It concerns our future.
I hate the way he's so flippant about such serious issues.