Source : Webster's Revised Unabridged Dictionary (1913)

Ruminant \Ru"mi*nant\, n. (Zo["o]l.)
   A ruminant animal; one of the Ruminantia.

Ruminant \Ru"mi*nant\, a. [L. ruminans, -antis, p. pr.: cf. F.
   ruminant. See {Ruminate}.] (Zo["o]l.)
   Chewing the cud; characterized by chewing again what has been
   swallowed; of or pertaining to the Ruminantia.

Source : WordNet®

ruminant
     adj : related to or characteristic of animals of the suborder
           Ruminantia or any other animal that chews a cud;
           "ruminant mammals" [ant: {nonruminant}]

ruminant
     n : any of various cud-chewing hoofed mammals having a stomach
         divided into four (occasionally three) compartments