random

Having no specific pattern, purpose, or objective: synonym: chance.

Of or relating to a type of circumstance or event that is described by a probability distribution.

Of or relating to an event in which all outcomes are equally likely, as in the testing of a blood sample for the presence of a substance.

(at random) Without a governing design, method, or purpose; unsystematically.

In mining, the direction of a rake-vein.