1. a trial or test period during which a new employee is allowed to work but is closely monitored to see if he is satisfactory. Usually a person is only a provisionalemployee during a probationary period and is subject to immediate dismissal if found unsatisfactory or becomes a permanent employee if found satisfactory. 2. any trial or test period during which a new product, process, machine, etc., is tried out often on a limited basis and monitored closely to determine whether to utilize it or discontinue its use.