centerbit

from The Century Dictionary.

• noun A carpenters' boring-tool, having a central point or pivot and two wings, called a scriber, or vertical cutting edge for severing the fibers in a circular path, and a router, which cuts horizontally and removes the wood within the circle of the scriber. See bit, 5.

from the GNU version of the Collaborative International Dictionary of English.

• noun An instrument turning on a center, for boring holes. See bit, n., 3.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a bit with a sharp center point for guidance and two side cutters