adverb
US/ˌʌn.prəˈfeʃ.ən.ə.li/
UK/ˌʌn.prəˈfeʃ.ən.ə.li/
in a way that is not suitable or responsible for someone at work
In context
The waiter behaved unprofessionally when he argued with a customer in front of the whole restaurant.
Short entry. Full notes coming.