Meaning of pro re nata*

pro re na•ta

Pronunciation: (prō' re' nä'tä Eng. prō' rē' nā't&schwa, rā'), [key]
— Latin. Latin.
  1. for an unforeseen need or contingency.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.