Meaning of “careless” - Learner’s Dictionary

careless

adjective uk us /ˈkeələs/

B1 not giving enough attention to what you are doing:

It was very careless of you to forget your passport.
He was fined £250 for careless driving.
carelessly adverb
carelessness noun [ U ]

(Definition of “careless” from the Cambridge Learner’s Dictionary © Cambridge University Press)