Stochastic in data science and machine learning refers to a property by which a randomly determined process cannot perfectly estimate individual events or data points but can demonstrate a general pattern common to the entire set of data. In data science and physics, the term stochastic refers to events which occur without a formally set of rules and mathematical equations but is rather "random" in nature. The opposite of stochastic systems in this context are the deterministic systems, which are well-defined by mathematical equations.
