Definition of: mesonephros

(mes′ə·nef′rəs, mē′sə-) noun Biol.
The middle of three tubular organs found in connection with the primitive genitourinary apparatus, and formed later than the pronephros; the mid–kidney or Wolffian body. It is the permanent kidney in some animals, as amphibians. [<NL <MESO- + Gk. nephros kidney]
—mes′o·neph′ric adjective