Source : Webster's Revised Unabridged Dictionary (1913)

Testis \Tes"tis\, n.; pl. {Testes}. [L.] (Anat.)
   A testicle.

Source : WordNet®

testis
     n : one of the two male reproductive glands that produce
         spermatozoa and secrete androgens; "she kicked him in the
         balls and got away" [syn: {testicle}, {orchis}, {ball}, {ballock},
          {bollock}, {nut}, {egg}]
     [also: {testes} (pl)]