In a way that does not meet the standard people expect from someone doing a job — especially a job with training and rules behind it, like a doctor, teacher, lawyer, or nurse. The word covers two rather different complaints, and it helps to keep them apart. The first is about MANNERS at work: arriving late, shouting at a customer, posting rude things about your boss online, wearing beach clothes to a meeting. Nobody is hurt, but you look bad and you make your company look bad. The second is about SKILL and DUTY: a doctor who does not check a patient properly, an accountant who hides a mistake. Here there are real rules, and someone can lose their licence. In everyday speech people mostly mean the first one. You will hear "He behaved unprofessionally" or "The email was written unprofessionally" — it is a serious-sounding word, more formal than "rudely", and it is often chosen exactly because it sounds cool and official instead of angry. Note that it points at the BEHAVIOUR, not the person's ability: you can be a brilliant engineer and still act unprofessionally. There is also a much weaker, non-job use meaning "like an amateur, not neatly made" — "the sign was unprofessionally painted" — but this is less common than the behaviour sense.

不專業地；有失專業水準地（形容行為舉止時，台灣人口語更常說「很不專業」「沒有職業道德」）