carelessness · noun U /ˈkeə.ləs.nəs/Full view
B2 the state of being careless
Dictionary example:

It's the carelessness with which he just throws stuff on the floor that annoys me.

Learner example:

Please forgive my carelessness. I'd like to bring a new one like yours when I come to you next time. (First Certificate in English; B2; Japanese)

Cambridge University Press