By strict definition, it means 'without knowledge', refering to deities. That is, an agnostic does not claim to have any definite knowledge of the existance of deities/a deity.
It is often said that agnosticism is a stepping stone to atheism. There is truth to this, as often the transition from theism to atheism is travelled through agnosticism. However, this is not the only form of agnosticism. Agnosticism can also develop as a rejection of both atheism and theism, for a number of reasons. All three discuss divinity in different ways, so it is foolish to say that agnosticism is simply a stepping stone to atheism, or undecided secularism.
He used to be Jewish, but after taking a philosophy course he became agnostic.
She calls herself an agnostic instead of atheist, because she finds them disagreeable.
A holiday on the 25th of December. It is originally meant to celebrate the birth of Christ, but in recent times has also become a secular holiday of sorts, with Santa Claus as its icon. The celebration of Christmas varies between cultures form highly religious to highly secular, but in the West it is usually a combination. Some say, with good reason, that it has become overly commercial. Though its commercialization is parallel to its secularization, it is not an unavoidable result of secularization.