1. A modified muscular pouch behind the stomach in the alimentary canal of birds, having a thick lining and often containing ingested grit that aids in the breakdown of seeds before digestion.
2. A similar digestive organ found in certain invertebrates, such as the earthworm.

[Alteration of Middle English giser, from Old French, from Vulgar Latin *gicērium, from Latin gigēria, cooked entrails of poultry, probably from Persian jigar, liver.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.