The adjective stochastic describes something that has a random variable. You like to joke that the city buses follow a stochastic schedule because they arrive at random times at the various bus stops.

Stochastic is from the Greek word stokhastikos, meaning able to guess, with the root stokhos meaning a target––in Greek stokhos literally means a stick meant for archers to shoot at. The "guess" part of the original Greek work is still part of the word's meaning today: A stochastic process in a computer program, for example, is one where you can't predict what is going to happen in the program because of something random in it.

Definitions of stochastic
  1. adjective
    being or having a random variable
    “a stochastic variable”
    stochastic processes”
    lacking any definite plan or order or purpose; governed by or depending on chance
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