1911 Encyclopædia Britannica/Bit

BIT (from the verb “to bite,” either in the sense of a piece bitten off, or an act of biting, or a thing that bites or is bitten), generally, a piece of anything; the word is, however, used in various special senses, all derivable from its origin, either literally or metaphorically. The most common of these are (1) its use as the name of various tools, e.g. centre-bit; (2) a horse’s “bit,” or the metal mouth-piece of the bridle; (3) in money, a small sum of money of varying value (e.g. threepenny-bit), especially in the West Indies and southern United States.