stochastic
Concise Oxford English Dictionary © 2008 Oxford University Press:
stochastic /stəˈkastɪk/
▶adjective technical having a random probability distribution or pattern that can be analysed statistically but not predicted precisely.
– derivatives
stochastically adverb.
stochastically adverb.
– origin C17: from Gk stokhastikos, from stokhazesthai ‘aim at, guess’, from stokhos ‘aim’.
'stochastic' also found in these Oxford entries:

