open texture

noun
  1. philosophy the failure of natural languages to determine future usage, particularly the ability of predicates to permit the construction of borderline cases
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012