Source : Webster's Revised Unabridged Dictionary (1913)

Gristle \Gris"tle\, n. [OE. gristel, gristil, AS. gristl; akin
   to OFries. gristel, grestel. Perh. a dim. of grist but cf.
   OHG. krustila, krostela. Cf. {Grist}.] (Anat.)
   Cartilage. See {Cartilage}. --Bacon.

Source : WordNet®

gristle
     n : tough elastic tissue; mostly converted to bone in adults
         [syn: {cartilage}]