BIT

n. & v. --n. 1 a metal mouthpiece on a bridle, used to control a horse. 2 a (usu. metal) tool or piece for boring or drilling. 3 the cutting or gripping part of a plane, pincers, etc. 4 the part of a key that engages with the lock-lever. 5 the copper head of a soldering-iron. --v.tr. 1 put a bit into the mouth of (a horse). 2 restrain. øtake the bit between one's teeth 1 take decisive personal action. 2 escape from control. [OE bite f. Gmc, rel. to BITE]