1. 
   unascertainable
   [adj] - not able to be ascertained
   Found op http://www.webdictionary.co.uk/definition.php?query=unascertainable
   
   
2. 
   unascertainable
   undiscoverable adjective not able to be ascertained; resisting discovery
   Found op http://wordnetweb.princeton.edu/perl/webwn?s=unascertainable
   
   
3. 
   unascertainable
   1) Indeterminable 2) Not able to be ascertained 3) Undeterminable 4) Undiscoverable
   Found op http://www.mijnwoordenboek.nl/EN/crossword-dictionary/unascertainable/1
   
   

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