noun \ˈrü-mən\
plural ru·mi·na \-mə-nə\ or rumens

Definition of RUMEN

: the large first compartment of the stomach of a ruminant from which food is regurgitated for rumination and in which cellulose is broken down by the action of symbiotic microorganisms—called also paunch; compare abomasum, omasum, reticulum

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