A word that means "all-knowing," this is usually applied to God.
Problems with Omniscience
There is some dispute about what "all" actually means. Does God literally know everything, not only that has happened, but that also might happen? If so, then in what sense does free will exist? If all your decisions are known by God before you make them then it's not clear if you are really making any "choices" since all the things that you do are predestined.
In a universe with a truly omniscient God, the Calvinist doctrine of predestination would have to be true. This carries its own set of issues, as it implies that God intentionally creates people already knowing that they will wind up in hell.
Fundamentalist Christians believe in the infalibality of the Bible, yet there are arguable contrictions to the issue of God's omniscience.
And Adam and his wife hid themselves from the presence of the Lord, amongst the trees of the garden.
And they said unto him, Where is Sarah thy wife? And he said, Behold, in the tent.
Job 1:7, 2:2
And the Lord said unto Satan, Whence comest thou? Then Satan answered the Lord, and said, from going to and fro in the earth, and from walking up and down in it.
2 Chronicles 32:31
God left him, to try him, that he might know all that was in his heart.