1. 
   noninterchangeable
   [adj] - (mathematics or logic) such that the terms of an expression cannot be interchanged without changing the meaning
   Found op http://www.webdictionary.co.uk/definition.php?query=noninterchangeable
   
   
2. 
   noninterchangeable
   adjective such that the terms of an expression cannot be interchanged without changing the meaning; `the arguments of the symmetric relation, `is the father of`, are noninterchangeable`
   Found op http://wordnetweb.princeton.edu/perl/webwn?s=noninterchangeable
   
   
3. 
   noninterchangeable
   1) Asymmetric 2) Asymmetrical
   Found op http://www.mijnwoordenboek.nl/EN/crossword-dictionary/noninterchangeable/1
   
   

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