cavalier

US /ˌkæv.əlˈɪr/
UK /ˌkæv.əlˈɪr/
1.

showing a lack of proper concern; offhand.

:
•
Anne was irritated by his cavalier attitude
:
offhandindifferentcasualdismissiveinsouciantuninterestedunconcernedsuperciliouspatronizingcondescendinghaughtyarrogantloftylordlydisdainfulscornfulcontemptuousunceremoniousdiscourteousuncivilinsolentrudeglibungraciousperfunctorycursorycurtabrupttersebrusqueoffoffishtake-it-or-leave-it
:
thoughtful
1.

a supporter of King Charles I in the English Civil War.

:
Royalist
:
Roundheadparliamentarian
2.

a small spaniel of a breed with a moderately long, noncurly, silky coat.