Unprofessional (adjective)

1. Not conforming to the standards of one's profession; unbecoming.
2. Not displaying the skill, competence, or manners expected of a professional person.

Origin:

Late 19th century: from un- (expressing negation) + professional.

Examples:

1. Unprofessional behavior.
2. An unprofessional attitude.
3. Unprofessional conduct.
4. An unprofessional appearance.
5. An unprofessional manner.