Hi, I'm trying to come up with a good translation to spanish of the term "Envelope deformation" but I can't find any information on why it is called like that.
  Does it have anything to do with an envelope you use to send a letter (by snail mail)? Or maybe it has more to do with the verb "envelope" as in "wrap around" or "surround". Maybe it's someone's name.

  Any help appreciated,
  thanks in advance,
Lucas Vieites