ru·men 
(rmən)
(rmən)n. pl. ru·mi·na (-mə-nə) or ru·mens
The first division of the stomach of a ruminant animal, in which most food collects immediately after being swallowed and from which it is later returned to the mouth as cud for thorough chewing. Also called paunch.
[Latin rūmen; akin to Sanskrit romantha-, ruminant, chewing the cud.]
rumi·nal adj.