[sto.chas.tic] adj [Gk stochastikos skillful in aiming, fr. stochazesthai to aim at, guess at, fr. stochos target, aim, guess--more at sting] (1923) 1: random; specif: involving a random variable "a ~ process"
2: involving chance or probability: probabilistic "a ~ model of radiation-induced mutation" -- sto.chas.ti.cal.ly adv