Webster's Revised Unabridged Dictionary · 1913

Jag

Jag (jag) , noun

[Probably of Celtic origin; compare Welsh gag aperture, cleft, chink; akin to Ir. & Gael. gag.]

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. — Bp. Hacket
3.
(Botany) A cleft or division.
4.
A leather bag or wallet;
saddlebags. [Scottish]
5.
Enough liquor to make a man noticeably drunk; a small “load;” a time or case of drunkenness; -- esp. in phr. To have a jag on, to be drunk. [Slang, United States & Dialectal English]
Collocations (1)
Jag bolt , a bolt with a nicked or barbed shank which resists retraction, as when leaded into stone.

Jag , transitive verb

To cut into notches or teeth like those of a saw; to notch.
Collocations (1)
Jagging iron , a wheel with a zigzag or jagged edge for cutting cakes or pastry into ornamental figures.

Jag , noun

[Scot. jag, jaug, a leather bag or wallet, a pocket. Compare Jag a notch.]

A small load, as of hay or grain in the straw, or of ore. [Provincial English & Colloquial United States] — Forby

Jag , transitive verb

To carry, as a load; as, to jag hay, etc. [Provincial English & Colloquial United States]

JAG , noun

(Military) Same as Judge-Advocate General. [Acronym]

Also: J.A.G