The Collaborative International Dictionary of English v.0.48:

Dexter \Dex"ter\, n. [Prob. so named after the original
   breeder.]
   One of a breed of small hardy cattle originating from the
   Kerry breed of Ireland, valuable both for beef and milk. They
   are usually chiefly black, sometimes red, and somewhat
   resemble a small shorthorn in build. Called also Dexter
   Kerry.
   [Webster 1913 Suppl.]