1. [adj]  of or relating to or based on probability; "probabilistic quantum theory"
2. [adj]  of or relating to the Roman Catholic philosophy of probabilism

Relating to, or governed by, probability. The behaviour of a probabilistic system cannot be predicted exactly but the probability of certain behaviours is known. Such systems may be simulated using pseudo-random numbers. Evolutionary computation uses probabilistic processes to generate new (potential) solutions to a problem.

See also deterministic, non-probabilistic.