dissemble in WordNet English dictionary

1. behave unnaturally or affectedly
   "She's just acting"
   dissemble  pretend  act 
   
2. make believe with the intent to deceive
   "He feigned that he was ill"; "He shammed a headache"
   feign  sham  pretend  affect  dissemble 
   
3. hide under a false appearance
   "He masked his disappointment"
   dissemble  cloak  mask