\Giz"zard\, n. [F. g['e]sier, L. gigeria, pl., the
cooked entrails of poultry. Cf. {Gigerium}.]
1. (Anat.) The second, or true, muscular stomach of birds, in
   which the food is crushed and ground, after being softened
   in the glandular stomach (crop), or lower part of the
   esophagus; the gigerium.
2. (Zo["o]l.)
   (a) A thick muscular stomach found in many invertebrate
       animals.
   (b) A stomach armed with chitinous or shelly plates or
       teeth, as in certain insects and mollusks.
{Gizzard shad} (Zo["o]l.), an American herring ({Dorosoma
   cepedianum}) resembling the shad, but of little value.
{To fret the gizzard}, to harass; to vex one's self; to
   worry. [Low] --Hudibras.
{To stick in one's gizzard}, to be difficult of digestion; to
   be offensive. [Low]