Taper

A taper is a workpiece that narrows (or widens) gradually and consistently along its length, rather than staying a constant width or thickness -- tapered table and chair legs are the most familiar furniture example, but the same gradually-changing-angle geometry shows up in a dovetail joint's pins and tails, a hand plane's wedge, and countless other places. A dedicated tapering jig, holding the workpiece at a fixed angle as it's fed past a table saw blade or jointer, is the standard way to cut a long, consistent taper -- freehanding the same cut without a jig makes it very difficult to hold a perfectly consistent angle over any real length.