Feather. This does not refer to plumage of birds, but the fuzziness in a selection or mask or brush. If you will forgive the visual pun, the image right illustrates on the left panel a hard selection (low feathering) with sharp edges (zoomed in section at the bottom). In the right panel is a loose selection with large feathering, where the edges of the selection fade off into the background. Below is a comparison of a hard (low feathering) and soft (high feathering) brush .
