Definition of rumen in English:


Pronunciation /ˈro͞omən/ /ˈrumən/

nounrumens, rumina

  • The first stomach of a ruminant, which receives food or cud from the esophagus, partly digests it with the aid of bacteria, and passes it to the reticulum.

    ‘When calves are fed milk it is funnelled through the oesophageal groove to the true stomach, bypassing the rumen.’
    • ‘So mammals are unable to digest cellulose, except some ruminants that have cellulase-secreting bacteria in their rumens.’
    • ‘He was interested in improving digestive processes within the rumen, the first of the four stomachs of ruminant animals, where cellulose is broken down by bacteria.’
    • ‘Added fat at levels at or above 5% of the diet has been reported to impair fiber digestion in the rumen and to depress feed intake.’
    • ‘Energy from the grain apparently helps complete the conversion of nitrate to bacterial protein in the rumen.’


Early 18th century from Latin, literally ‘throat’.