Source : Webster's Revised Unabridged Dictionary (1913)

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.

   2. Roaring, as of waves breaking upon the shore; rote. See
      {Rote}.

Rut \Rut\, v. i. [imp. & p. p. {Rutted}; p. pr. & vb. n.
   {Rutting}.]
   To have a strong sexual impulse at the reproductive period;
   -- said of deer, cattle, etc.

Rut \Rut\, v. t.
   To cover in copulation. --Dryden.

Rut \Rut\, n. [variant of route.]
   A track worn by a wheel or by habitual passage of anything; a
   groove in which anything runs. Also used figuratively.

Source : WordNet®

rut
     n 1: a groove or furrow (especially one in soft earth caused by
          wheels)
     2: a settled and monotonous routine that is hard to escape;
        "they fell into a conversational rut" [syn: {groove}]
     3: applies to nonhuman mammals: a state or period of heightened
        sexual arousal and activity [syn: {estrus}, {oestrus}, {heat}]
        [ant: {anestrus}]
     [also: {rutting}, {rutted}]

rut
     v 1: be in a state of sexual excitement; of male mammals
     2: hollow out in the form of a furrow or groove; "furrow soil"
        [syn: {furrow}, {groove}]
     [also: {rutting}, {rutted}]