The Collaborative International Dictionary of English v.0.48:

Jag \Jag\ (j[a^]g), n. [Prob. of Celtic origin; cf. W. gag
   aperture, cleft, chink; akin to Ir. & Gael. gag.] [Written
   also jagg.]
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   1. A notch; a cleft; a barb; a ragged or sharp protuberance;
      a denticulation.
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            Arethuss arose . . .
            From rock and from jag.               --Shelley.
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            Garments thus beset with long jags.   --Holland.
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   2. A part broken off; a fragment. --Bp. Hacket.
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   3. (Bot.) A cleft or division.
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   4. A leather bag or wallet; pl., saddlebags. [Scot.]
      [Webster 1913 Suppl.]

   5. Enough liquor to make a man noticeably drunk; a small
      "load;" a time or case of drunkeness; -- esp. in phr. To
      have a jag on, to be drunk. [Slang, U. S. & Dial. Eng.]
      [Webster 1913 Suppl.]

   Jag bolt, a bolt with a nicked or barbed shank which
      resists retraction, as when leaded into stone.
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The Collaborative International Dictionary of English v.0.48:

jagg \jagg\, v. t. & n.
   See Jag.
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The Collaborative International Dictionary of English v.0.48:

Jag \Jag\, v. t. [imp. & p. p. Jagged; p. pr. & vb. n.
   Jagging.]
   To cut into notches or teeth like those of a saw; to notch.
   [Written also jagg.]
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   Jagging iron, a wheel with a zigzag or jagged edge for
      cutting cakes or pastry into ornamental figures.
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The Collaborative International Dictionary of English v.0.48:

Jag \Jag\, n. [Scot. jag, jaug, a leather bag or wallet, a
   pocket. Cf. Jag a notch.]
   A small load, as of hay or grain in the straw, or of ore.
   [Prov. Eng. & Colloq. U.S.] [Written also jagg.] --Forby.
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