JAG

Jag (?), n. [[Prob. of Celtic origin; cf. W. gag aperture, cleft, chink; akin to Ir. & Gael. gag.]] [Written also jagg.] 1. 1. A notch; a cleft; a barb; a ragged or sharp protuberance; a denticulation.
Arethuss arose . . . From rock and from jag. Shelley. Garments thus beset with long jags. Holland. 2. 2. A part broken off; a fragment. Bp. Hacket.
3. 3. (Bot.) A cleft or division.
Jag bolt, a bolt with a nicked or barbed shank which resists retraction, as when leaded into stone.