Something billows when there's a fluid or blowing motion, such as the air filling a curtain at an open window, or smoke billowing from a fire.

This word originally meant a wave, and that image should help you remember its current meaning too. The word usually suggests movement and growth, such as waves building and crashing. There are certain clouds that look like ocean waves, and so are called billow clouds. If you have a big shirt, the wind might make it fill with air and billow. Balloons are billowed when you inflate them. Billowing can also mean to move with difficulty — slowly.

Definitions of billow
  1. noun
    a large sea wave
    synonyms: surge
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    type of:
    moving ridge, wave
    one of a series of ridges that moves across the surface of a liquid (especially across a large body of water)
  2. verb
    rise up as if in waves
    “smoke billowed up into the sky”
    synonyms: wallow
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    billow up in the form of a cloud
    type of:
    soar, soar up, soar upwards, surge, zoom
    rise rapidly
  3. verb
    rise and move, as in waves or billows
    synonyms: heave, surge
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    type of:
    blow up, inflate
    fill with gas or air
  4. verb
    move with great difficulty
    “The soldiers billowed across the muddy riverbed”
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    type of:
    go, locomote, move, travel
    change location; move, travel, or proceed, also metaphorically
  5. verb
    become inflated
    synonyms: balloon, inflate
    see moresee less
    become inflated again
    type of:
    become larger in size or volume or quantity
Word Family

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