cav ‧ a ‧ lier /ˌkævəˈlɪə◂ $ -ˈlɪr◂/ BrE AmE adjective [usually before noun]
[ Date: 1500-1600 ; Language: French ; Origin: Old Italian cavaliere , from Late Latin caballarius 'horse-rider' , from Latin caballus 'horse' ]
not caring enough about rules, principles, or people’s feelings:
a cavalier attitude to the laws