roar in WordNet English dictionary

1. a very loud utterance (like the sound of an animal)
   "his bellow filled the hallway"
   bellow  bellowing  holla  holler  hollering  hollo  holloa  roar  roaring  yowl 
   
2. a deep prolonged loud noise
   boom  roar  roaring  thunder 
   
3. the sound made by a lion
   roar 
   

1. make a loud noise, as of animal
   "The bull bellowed"
   bellow  roar 
   
2. laugh unrestrainedly and heartily
   roar  howl 
   
3. make a loud noise, as of wind, water, or vehicles
   "The wind was howling in the trees"; "The water roared down the chute"
   roar  howl 
   
4. emit long loud cries
   "wail in self-pity"; "howl with sorrow"
   howl  ululate  wail  roar  yawl  yaup 
   
5. utter words loudly and forcefully
   "`Get out of here,' he roared"
   thunder  roar 
   
6. act or proceed in a riotous, turbulent, or disorderly way
   "desperadoes from the hills regularly roared in to take over the town"-R.A.Billington
   roar