Source : Webster's Revised Unabridged Dictionary (1913)

Low \Low\, v. i. [imp. & p. p. {Lowed}; p. pr. & vb. n.
   {Lowing}.] [OE. lowen, AS. hl?wan; akin to D. loeijen, OHG.
   hl?jan, hluojan.]
   To make the calling sound of cows and other bovine animals;
   to moo.

         The lowing herd wind slowly o'er the lea. --Gray.

Lowing \Low"ing\, n.
   The calling sound made by cows and other bovine animals.