unprofessional
adj.adj. behaving in a way that does not meet the high standards expected at work. You use this to describe someone who is rude, messy, or lazy in a business setting.
adj. below the standards of behavior or competence expected in a particular profession. Often used to describe a lack of etiquette, reliability, or ethical conduct in a workplace context.
It is unprofessional to check your phone during a meeting.
The client felt that the constant spelling errors in the proposal were highly unprofessional and decided to hire a different firm.
While the technical advice was sound, the consultant's unprofessional habit of disparaging former colleagues during lunch made the executive team hesitant to offer him a long-term contract.
Typically used attributively before a noun or predicatively after linking verbs like 'be', 'seem', or 'appear'.