A sprite is just a 2D image. Animation in old 2D games would usually store several frames of animation in a single image, similar to the current use in CSS.
http://en.wikipedia.org/wiki/Sprite_(computer_graphics)
This dates back to the Commodore 64, that said do we really need to down vote this guy so much. He was misinformed. This doesn't mean we have to be vindictive.
Anyhow, it's just terminology. I still hate it.