\U`ni*form`i*ta"ri*an\, a. (Geol.)
Of, pertaining to, or designating, the view or doctrine that
existing causes, acting in the same manner and with
essentially the same intensity as at the present time, are
sufficient to account for all geological changes.

\U`ni*form`i*ta"ri*an\, n. (Geol.)
One who accepts uniformitarianism, or the uniformitarian
doctrine.