agnosticism

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The doctrine that certainty about first principles or absolute truth is unattainable and that only perceptual phenomena are objects of exact knowledge.
2. n. The belief that there can be no proof either that God exists or that God does not exist.

Century Dictionary and Cyclopedia

1. n. The doctrines of the agnostics; the doctrine that the ultimate cause and the essential nature of tilings are unknowable, or at least unknown.
2. n. Belief in the doctrines of the agnostics.

Wiktionary

1. n. The view that absolute truth or ultimate certainty is unattainable, especially regarding knowledge not based on experience or perceivable phenomena.
2. n. The view that the existence of God or of all deities is unknown, unknowable, unproven, or unprovable.
3. n. Doubt, uncertainty, or scepticism regarding the existence of a God or of all deities.

GNU Webster's 1913

1. n. That doctrine which, professing ignorance, neither asserts nor denies. 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 furnished by physical and physical data, to warrant a positive conclusion (as taught by the school of Herbert Spencer); -- opposed alike dogmatic skepticism and to dogmatic theism.

WordNet 3.0

1. n. the disbelief in any claims of ultimate knowledge
2. n. a religious orientation of doubt; a denial of ultimate knowledge of the existence of God