I kind of always thought that a sprite was always animated, but the term sprite just refers to a static image as well. So basically I am creating a sort of stop motion animation by changing poses of the character quickly?
How else do you think animation is done? It's all stop motion basically, but so quickly that it's fluid.
EDIT:I should mention though, that if you only need to move an arm or head, you don't need multiple sprites. You could have an image of the arm or head move on a static image of the body.