1. 
   strenuous
   [adj] - characterized by or performed with much energy or force
   Found op http://www.webdictionary.co.uk/definition.php?query=strenuous
   
   
2. 
   Strenuous
   Stren'u·ous adjective [ Latin strenuus ; confer Greek ... strong, hard, rough, harsh.] Eagerly pressing or urgent; zealous; ardent; earnest; bold; valiant; intrepid; as, a strenuous advocate for national rights; a strenuous reformer;...
   Found op http://www.encyclo.co.uk/webster/S/209
   
   
3. 
   strenuous
   adjective characterized by or performed with much energy or force; `strenuous exercise`
   Found op http://wordnetweb.princeton.edu/perl/webwn?s=strenuous
   
   
4. 
   Strenuous
   • (a.) Eagerly pressing or urgent; zealous; ardent; earnest; bold; valiant; intrepid; as, a strenuous advocate for national rights; a strenuous reformer; a strenuous defender of his country.
   Found op http://thinkexist.com/dictionary/meaning/strenuous/
   
   
5. 
   strenuous
   1) Energetic
   Found op http://www.mijnwoordenboek.nl/EN/crossword-dictionary/strenuous/1
   
   

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