droop in WordNet English dictionary

1. a shape that sags
   "there was a sag in the chair seat"
   sag  droop 
   

1. become limp
   "The flowers wilted"
   wilt  droop 
   
2. droop, sink, or settle from or as if from pressure or loss of tautness
   sag  droop  swag  flag 
   
3. hang loosely or laxly
   "His tongue lolled"
   droop  loll