American National Standard B94.11M-1993 covers the relevant information relating to drill bits, including sizes, tolerances, nomenclature, and definitions. Below is a summary of some of the key terminology relating to drill bits.

Axis – refers to a centerline running down the middle of the drill bit longitudinally from the point of the drill bit to the end of the body.

Back taper – is a reduction in the drill bit’s diameter that occurs from the point of the drill bit to the end of the drill bit body. Most drill bits are machined with a small back taper to prevent the bit from binding in the workpiece when the drill bit becomes worn.

Body – refers to the portion of the drill bit that extends from the neck to the outer edges of the cutting lips and which contains the flutes.

Drill Diameter – the overall diameter of the drill bit measured at the point of the drill up to the margins.

Flutes – are the grooves that are formed in the drill bit which serve to allow the removal of chips from the hole being cut and to allow cutting fluid to reach the cutting lips of the bit. Flutes are usually helically shaped or straight cut.

Lips – the cutting surfaces of the drill bit.

Neck – a small section of the drill bit which has a reduced diameter that sites between the shank of the bit and the body.

Overall length – is the distance measured from the extreme end of the shank to the outer corners of the cutting lips. Note that this measurement excludes the conical shank end and the conical cutting point at the tip of the drill bit.

Point angle – the angle that is formed between the lips when a projection is made onto a planar surface that runs parallel to the axis of the drill bit and to the cutting lips.

Shank – the portion of the drill bit by which it is held in place and driven, i.e. the portion that does not contain flutes.