1. A reference to, characterized by, or skilled in conjecture; conjectural.
2. Subject to the laws of probability; not predictable within a given time limit or spatial framework, as the disintegration of a single radioactive element; such as, the stochastic phenomena of microphysics.
3. Denoting the process of selecting, from among a group of theoretically possible alternatives, those elements or factors whose combination will most closely approximate a desired result; such as, a stochastic model.
4. In cybernetics, partially random or uncertain, not continuous; a stochastic variable is neither completely determined nor completely random; in other words, it contains an element of probability. A system containing one or more stochastic variables is probabilistically determined.
5. Etymology: from "pertaining to conjecture"; from Greek stokhastikos, "able to guess, conjecturing"; from stokhazesthai, "guess", from stokhos, "a guess, aim, target, mark"; literally, "pointed stick set up for archers to shoot at".

The sense of "randomly determined" is first recorded in 1934, from German Stochastik.

An analysis related to a process involving a randomly determined sequence of observations, each of which is considered as a sample of one element from a probability distribution.

A device, with a finite number of internal states, that scans words over a finite alphabet, with the next state determined according to probabilistic functions of the current input word.

A branch of control theory that attempts to predict and to minimize the magnitudes and limits of random deviations in a control system by optimizing the design of the controller.

The gathering; that is, the focusing of clouds of subatomic particles in an accelerator by monitoring their scattering vectors and altering the magnetic environment in an accelerator storage ring to keep them close together.

First employed in storing particles of antimatter, which are expensive to manufacture and should not be wasted.

A square matrix with non-negative real entries such that the sum of the entries of each row equals one.

If, in addition, the sum of the entries in each column equals one, the matrix is said to be doubly stochastic.

A mathematical model that contains uncertainties or random variables.

A family of random variables, dependent upon a parameter which usually denotes time.