cavalier
adj. C1 Advanced US //ˈkævəɫiɹ// UK //kˌævɐlˈiə// cav·a·lier
adj. showing a lack of proper concern or care. You use this to describe someone who treats serious matters as if they are not important.
adj. marked by a lack of proper concern; dismissive of serious matters or consequences. Often used predicatively after linking verbs like 'be' or 'seem'.
He has a cavalier attitude toward his safety.
The manager's cavalier dismissal of the safety concerns upset many of the factory workers.
Such a cavalier approach to international law risks alienating long-term allies and destabilising the fragile peace that has held for decades.
Usage
Often used to modify nouns like 'attitude', 'disregard', or 'treatment'.