Chamfer
A chamfer is a transitional edge between two vertices of an object. It can also be known as a bevel but connotes more often cutting and more often 45°. If the un-chamfered intersection of the adjoining faces would otherwise form a right angle, 90° as is most common, the chamfer will typically be uniform and pitched at 45°. A fully chamfered square interior would thus be octagonal. (By contrast, a fillet is the rounding off of an interior corner, and a rounding of an exterior corner is called a "round". or a "radius")
"Chamfer" is a term commonly used in mechanical and manufacturing engineering. Special tools such as chamfer mills and chamfer planes are available. In tile work, or furniture such as counters or table tops, an edge or arris that has been eased by rounding instead of chamfering is called a bullnose. Where a chamfer does not go to the end of the piece, but "lifts out" in a smooth curve, the end is called a lark's tongue usually seen as a pair in these fields.