APA Dictionary of Psychology

a random process: a sequence of events with a random probability pattern such that the occurrence of any event in the sequence is independent of past events. For example, the number of people in a doctor’s office who have colds during a 1-month period could be said to follow a stochastic process. In contrast to deterministic processes, stochastic processes involve some indeterminacy, and their development over time may only be described by probability distributions. A Markov chain is a stochastic process.