1. 
   Aperature
   The opening in pipes.
   Found op http://www.rookinspections.com/glossary/glossarya.shtml
   
   
2. 
   Aperature
   An opening; in solar collectors, the area through which solar radiation is admitted and directed to the absorber.
   Found op http://www.electromn.com/glossary/a.htm
   
   
3. 
   aperature
   1) The opening in pipes
   Found op http://www.mijnwoordenboek.nl/EN/crossword-dictionary/aperature/1
   
   

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