1. 
   impugned
   challenged to be doubted 
   Found op http://www.graduateshotline.com/list.html
   
   
2. 
   Impugned
   • (imp. & p. p.) of Impugn
   Found op http://thinkexist.com/dictionary/meaning/impugned/
   
   
3. 
   impugned
   1) Attacked verbally 2) Challenged to be doubted 3) Questioned
   Found op http://www.mijnwoordenboek.nl/EN/crossword-dictionary/impugned/1
   
   

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