1. 
   VSI
   Virtual Socket/Switch Interface
   Found op http://www.encyclo.co.uk/visitor-contributions.php
   
   
2. 
   VSI
   (Aviation abbreviations:) vertical speed indicator
   Found op http://www.aviationonline.co.uk/glossary/uz.htm
   
   
3. 
   VSI
   Very Seriously Ill
   Found op http://www.encyclo.co.uk/visitor-contributions.php
   
   
4. 
   VSI
   Vertical Speed Indicator. A panel instrument that gauges rate of climb or descent in feet-per-minute (fpm). Also Rate Of Climb Indicator.
   Found op http://www.aerofiles.com/glossary.html
   
   
5. 
   vsi
   1) Virtual socket&slash;switch interface
   Found op http://www.mijnwoordenboek.nl/EN/crossword-dictionary/vsi/1
   
   

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