A chamfer is any beveled edge that is utilized to join two surfaces. For instance, in the case of joining or connecting two pieces of wood at right angles, the chamfer would typically be a 45 degree piece in the angle. The opposite of a chamfer is a fillet, which is the rounding of an interior corner.
Common uses of a chamfer
The most common use of a chamfer is to create a look which removes the look of a sharp edge. Another definition of a chamfer is a groove cut into a column, as in Roman columns, usually cut into stone.
However, the beveled molding is the more common definition of chamfer in construction. A crown molding or other such decorative moldings would be an example of a chamfer. A chamfer is usually not a supportive or functional piece, but rather is usually decorative or esthetic.
Special tools to make chamfers
There are special tools available to create chamfers, such as chamfer mills or chamfer planes.