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. A part broken off; a fragment.
3. (Science: botany) a cleft or division. Jag bolt, a bolt with a nicked or barbed shank which resists retraction, as when leaded into stone.
Origin: Prob. Of Celtic origin; cf. W. Gag aperture, cleft, chink; akin to ir. & gael. Gag
alternative forms: jagg.