sto·chas·tic 
(stō-kăstĭk)
(stō-kăstĭk)adj.
1. Of, relating to, or characterized by conjecture; conjectural.
2. Statistics Involving or containing a random variable or process: stochastic calculus; a stochastic simulation.
[Greek stokhastikos, from stokhastēs, diviner, from stokhazesthai, to guess at, from stokhos, aim, goal; see stegh- in the Appendix of Indo-European roots.]
sto·chasti·cal·ly adv.