1870, from agnostic + -ism. The agnostic does not simply say, "I do not know." He goes another step, and he says, with great emphasis, that you do not know. [Robert G. Ingersoll, "Reply [..]

introduced by Thomas Henry Huxley, a biologist, the non-believing state of retaining a concept that the certainty or falsehood of specific supernatural concepts or postulations can't be proven. O [..]

(n) a religious orientation of doubt; a denial of ultimate knowledge of the existence of God(n) the disbelief in any claims of ultimate knowledge

Usually used to mean denying the possibility of knowing the nature or existence of God, but used by Marxists with the meaning of denying the possibility of knowledge of the objective world. Agnosticis [..]

The position of agnostics is that the existence or non-existence of god is unproven, but that either of these truths is a possibility. Typically they do not involve themselves in any form of worship, [..]

That doctrine which, professing ignorance, neither asserts nor denies. Specifically: The doctrine that the existence of a personal Deity, an unseen world, etc, can be neither proved nor disproved, because of the necessary limits of the human mind (as sometimes charged upon Hamilton and Mansel), or because of the insufficiency of the evidence furnis [..]

The conviction that one simply does not know whether God exists or not; it is often accompanied with a further conviction that one need not care whether God exists or not.