Stochasticity

Refers to any process in which there is a random variable or element of probability in its structure, and which as such depends on some parameter that may be discrete or continuous.  In a stochastic process consisting of a sequence of discrete events, the outcome of one event has no bearing on the outcome of any other. 

See Hidden Markov model (HMM), Motor noise, Perception-action coupling, Quantum mechanics, Time-series