Source : Webster's Revised Unabridged Dictionary (1913)

Jenny \Jen"ny\, n.; pl. {Jennies}.
   1. A familiar or pet form of the proper name Jane.

   2. (Zo["o]l.) A familiar name of the European wren.

   {Jenny ass} (Zo["o]l.), a female ass.

Source : WordNet®

jenny ass
     n : female donkey [syn: {jennet}, {jenny}]