Source : Webster's Revised Unabridged Dictionary (1913)

Rhesus \Rhe"sus\, n. [L. Rhesus, a proper name, Gr. ???.]
   (Zo["o]l.)
   A monkey; the bhunder.

Source : WordNet®

rhesus
     n : of southern Asia; used in medical research [syn: {rhesus
         monkey}, {Macaca mulatta}]