rumen
/ˈruːmən/
noun
- The first and largest part of the stomach of a cow, sheep, or other ruminant animal, where food is stored and partially digested before being regurgitated and chewed again.
- Farmers sometimes check the health of a cow by feeling its rumen.
- The cow's rumen contains billions of bacteria that help break down grass.
- Scientists study the microbes in the rumen to improve animal digestion.