gizzard (n.)

"stomach of a bird," late 14c., from Old French gisier "entrails, giblets (of a bird)" (13c., Modern French gésier), probably from Vulgar Latin *gicerium, a dissimilation of Latin gigeria (neuter plural) "cooked entrails of a fowl," a delicacy in ancient Rome, from PIE *yekwr- "liver" (see hepatitis). The unetymological -d was added 1500s (perhaps on analogy of -ard words). Later extended to other animals, and, jocularly, to human beings (1660s).