Rut \Rut\, n. [F. rut, OF. ruit, L. rugitus a roaring, fr. rugire to roar; -- so called from the noise made by deer in rutting time.] 1. (Physiol.) Sexual desire or [oe]strus of deer, cattle, and various other mammals; heat; also, the period during which the [oe]strus exists. [1913 Webster] 2. Roaring, as of waves breaking upon the shore; rote. See {Rote}. [1913 Webster]