not caring about other people’s feelings or about the seriousness of a situation
a supporter of the king in the English Civil War of the 17th century
Origin and usage
A cavalier was originally a horseman, and especially a knight. This meaning came into English in the 16th century and is related to the Spanish ‘caballero’, the French ‘chevalier’ and the Italian ‘cavaliere’, all ultimately from the Latin word for horse, ‘caballus’. The adjective dates from the mid 17th century.
The noun cavalier had already been used in English for half a century when it started to be applied to the supporters of King Charles I in the Civil War. This meaning, which soon came to be spelled Cavalier to distinguish it from the general meaning, was initially used as a term of abuse. Distinguished from the Puritan supporters of Parliament by their long hair and elaborate clothing, the Cavaliers – who ended up on the losing side, along with the King, who was executed in 1649 – were memorably described in the humorous history book ‘1066 and All That’ as ‘Wrong but Wromantic’ (the Puritans or Roundheads were ‘Right but Repulsive‘). The adjective cavalier, which is used to describe people or actions that are careless of the sensitivities of others or the seriousness of a situation, reflects the buccaneering nonchalance atttributed to the historical Cavaliers.
“In short, he was a perfect cavaliero,/ And to his very valet seemed a hero.”
“If trees could scream, would we be so cavalier about cutting them down?”
careless, detached, unfeeling