It's the thick-walled muscular pouch that grinds food in a bird's lower stomach
[DOC] [TLE] Gizzard - definition of gizzard by The Free Dictionary [PAR] A modified muscular pouch behind the stomach in the digestive tract of birds, 
having a ... (Zoology) the thick-walled part of a bird's stomach, in which hard food 
is ... the thick-walled, muscular lower stomach of many birds and reptiles that 
grinds ... not a turkey but he beheld daintily trussed up, with its gizzard under its 
wing,... [DOC] [TLE] Gizzards - definition of Gizzards by The Free Dictionary [PAR] A modified muscular pouch behind the stomach in the digestive tract of birds, 
having a ... (Zoology) the thick-walled part of a bird's stomach, in which hard food 
is ... the thick-walled, muscular lower stomach of many birds and reptiles that 
grinds ... not a turkey but he beheld daintily trussed up, with its gizzard under its 
wing,... [DOC] [TLE] Quia - Chap 13 Birds and Mammals [PAR] crop, a bird's internal storage tank that allows it to store food inside its body after 
... gizzard, a thick-walled, muscular part of a bird's stomach that squeezes and 
grinds ... the difference in pressure between the upper and lower surfaces of the 
object ... and which usually continue to develop in a pouch on their mother's body
.