The Collaborative International Dictionary of English v.0.48:

Endysis \En"dy*sis\, n.; pl. Endyses. [NL., fr. Gr. ? a
   putting on, fr. ? to put on.] (Biol.)
   The act of developing a new coat of hair, a new set of
   feathers, scales, etc.; -- opposed to ecdysis.
   [1913 Webster]