as a geological or biological theory (opposed to uniformitarianism), 1869, coined by T.H. Huxley from catastrophe + -ism. Related: Catastrophist.
By CATASTROPHISM I mean any form of geological speculation which, in order to account for the phenomena of geology, supposes the operation of forces different in their nature, or immeasurably different in power, from those which we at present see in action in the universe. [Huxley, "Address" to the Geological Society of London, Feb. 19, 1869]