Fit \Fit\, n. 1. The quality of being fit; adjustment; adaptedness; as of dress to the person of the wearer. 2. (Mach.) (a) The coincidence of parts that come in contact. (b) The part of an object upon which anything fits tightly. {Fit rod} (Shipbuilding), a gauge rod used to try the depth of a bolt hole in order to determine the length of the bolt required. --Knight.