Source : Webster's Revised Unabridged Dictionary (1913)

Jagger \Jag"ger\, n. [From 4th {Jag}.]
   One who, or that which, jags; specifically:
   (a) jagging iron used for crimping pies, cakes, etc.
   (b) A toothed chisel. See {Jag}, v. t.

   {Jagger spring}, a spring beneath a seat, and resting on
      cleats or blocks in the body of a vehicle. --Knight.