grey area

noun
  1. (in Britain) a region in which unemployment is relatively high
  2. an area or part of something existing between two extremes and having mixed characteristics of both
  3. an area, situation, etc, lacking clearly defined characteristics
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