gizzard vs gastric mill

gizzard and gastric mill both are nouns.

Word	Noun	Adjective	Verb	Adverb
gizzard	Yes	No	No	No
gastric mill	Yes	No	No	No

As nouns, gizzard and gastric mill are synonyms defined as:

gizzard and gastric mill: thick-walled muscular pouch below the crop in many birds and reptiles for grinding food

Other synonyms of gizzard include ventriculus.

gizzard (noun)	gastric mill (noun)
thick-walled muscular pouch below the crop in many birds and reptiles for grinding food	thick-walled muscular pouch below the crop in many birds and reptiles for grinding food