billow in WordNet English dictionary

1. become inflated
   "The sails ballooned"
   balloon  inflate  billow 
   
2. rise and move, as in waves or billows
   "The army surged forward"
   billow  surge  heave 
   
3. rise up as if in waves
   "smoke billowed up into the sky"
   billow  wallow 
   
4. move with great difficulty
   "The soldiers billowed across the muddy riverbed"
   billow 
   

1. a large sea wave
   billow  surge