What is the meaning of billow?

noun

• A large sea wave.
  • synonyms: surge

verb

• Rise up as if in waves.
  • usage: "smoke billowed up into the sky"
  • synonyms: wallow
• Move with great difficulty.
  • usage: "The soldiers billowed across the muddy riverbed"
• Rise and move, as in waves or billows.
  • usage: "The army surged forward"
  • synonyms: surge, heave
• Become inflated.
  • usage: "The sails ballooned"
  • synonyms: balloon, inflate