thresh in WordNet English dictionary

1. move or stir about violently
   "The feverish patient thrashed around in his bed"
   convulse  thresh  thresh about  thrash  thrash about  slash  toss  jactitate 
   
2. give a thrashing to; beat hard
   thrash  thresh  lam  flail 
   
3. move like a flail; thresh about
   "Her arms were flailing"
   flail  thresh 
   
4. beat the seeds out of a grain
   thrash  thresh