Merriam-Webster's Collegiate® Dictionary, 11th Edition
BIT
I. noun
Etymology: Middle English bitt, from Old English bite act of biting; akin to Old English bītan bite
Date: 14th century
1. a. the biting or cutting edge or part of a tool, a replaceable part of a compound tool that actually performs the function (as drilling or boring) for which the whole tool is designed, the jaws of tongs or pincers, something bitten or held with the teeth:, the usually steel part of a bridle inserted in the mouth of a horse, the rimmed mouth end on the stem of a pipe or cigar holder, something that curbs or restrains, the part of a key that enters the lock and acts on the bolt and tumblers,
II. transitive verb (bitted; bitting)
Date: 1583
1. to put a bit in the mouth of (a horse), to control as if with a bit, to form a bit on (a key),
III. noun
Etymology: Middle English, from Old English bita; akin to Old English bītan bite Date: before 12th century a small quantity of food,
2. a small piece or quantity of some material thing, b. a small coin, a unit of value equal to 1/8 of a dollar, something small or unimportant of its kind: as, a brief period ; while , an indefinite usually small degree, extent, or amount , c. a small part usually with spoken lines in a theatrical performance, a usually short theatrical routine , the aggregate of items, situations, or activities appropriate to a given style, genre, or role ,
IV. noun
Etymology: binary digit
Date: 1948
a unit of computer information equivalent to the result of a choice between two alternatives (as yes or no, on or off ), the physical representation of a bit by an electrical pulse, a magnetized spot, or a hole whose presence or absence indicates data