I looked it up, and here's what I found:
Agnosticism is the philosophical view that the truth values of certain claims, particularly theological claims regarding the existence of God, gods or deities, are either unknown or inherently unknowable. The term and the related agnostic were coined by Thomas Henry Huxley in 1869 and are also used to describe those who are unconvinced or noncommittal about the existence of deities as well as other matters of religion. The word agnostic comes from the Greek a (without) and gnosis (knowledge). Agnosticism is not to be confused with a view specifically opposing the doctrine of gnosis and Gnosticism - these are religious concepts that are not generally related to agnosticism.
Agnosticism is distinct from strong atheism in that strong atheists claim there is no God, whereas agnostics don't claim to know anything about any God or even claim not to (be able to) know anything about any God. However the more general class of atheism, weak atheism, only depends upon lack of belief in god. In the sense that weak atheism is everything not theist, it could be said that technically agnosticism is a subset of weak atheism, as the agnostic lacks belief in deities, and is therefore not a theist. Agnosticism can also be defined to be on the borderline of theism and weak atheism, being neither. In such a case agnosticism implies a sort of (theoretical) neutrality between the two, something not categorical by belief or lack of belief. The precise definition of agnosticism will vary and claims of belief are not necessarily consistent for individual theists, atheists, or agnostics.
It is possible to hold both agnostic and atheistic views at once, depending on the god being discussed at the time. For example, a person may assert that a particular deity with impossible or contradictory attributes cannot logically exist (strong atheism), whereas a different deity remains merely unknowable.
Agnostics may claim that it isn't possible to have absolute or certain spiritual knowledge; alternatively they may claim that while certainty may be possible, they personally have no such knowledge. Agnosticism in both cases involves scepticism towards religious statements.
Agnosticism is distinct from strong atheism in that strong atheists claim there is no God, whereas agnostics don't claim to know anything about any God or even claim not to (be able to) know anything about any God. However the more general class of atheism, weak atheism, only depends upon lack of belief in god. In the sense that weak atheism is everything not theist, it could be said that technically agnosticism is a subset of weak atheism, as the agnostic lacks belief in deities, and is therefore not a theist. Agnosticism can also be defined to be on the borderline of theism and weak atheism, being neither. In such a case agnosticism implies a sort of (theoretical) neutrality between the two, something not categorical by belief or lack of belief. The precise definition of agnosticism will vary and claims of belief are not necessarily consistent for individual theists, atheists, or agnostics.
It is possible to hold both agnostic and atheistic views at once, depending on the god being discussed at the time. For example, a person may assert that a particular deity with impossible or contradictory attributes cannot logically exist (strong atheism), whereas a different deity remains merely unknowable.
Agnostics may claim that it isn't possible to have absolute or certain spiritual knowledge; alternatively they may claim that while certainty may be possible, they personally have no such knowledge. Agnosticism in both cases involves scepticism towards religious statements.