"In the popular sense, an agnostic is someone who neither believes nor disbelieves in God, whereas an atheist disbelieves in God. In the strict sense, however, agnosticism is the view that human reason is incapable of providing sufficient rational grounds to justify either the belief that God exists or the belief that God does not exist. In so far as one holds that our beliefs are rational only if they are sufficiently supported by human reason, the person who accepts the philosophical position of agnosticism will hold that neither the belief that God exists nor the belief that God does not exist is rational." Rowe, William L. (1998 ). "Agnosticism". -- In Edward Craig. Routledge Encyclopedia of Philosophy. Taylor & Francis. ISBN 978-0-415-07310-3.
"agnostic. A. n. 1. A person who believes that nothing is known or can be known of immaterial things, especially of the existence or nature of God. Also: person of indeterminate ideology or conviction; an equivocator. B. adj. 1. Of or relating to the belief that the existence of anything beyond and behind material phenomena is unknown and (as far as can be judged) unknowable. Also: holding this belief." --"agnostic, agnosticism". OED Online, 3rd ed. Oxford University Press. September 2012.
See post directly above for an example of what has been previously mentioned.