Source : Webster's Revised Unabridged Dictionary (1913)

Stirk \Stirk\, n. [AS. stric, from ste['o]r a steer. See {Steer}
   a young ox.]
   A young bullock or heifer. [Prov. Eng. & Scot.] --Sir W.
   Scott.

Source : WordNet®

stirk
     n : yearling heifer or bullock