billowing

/B IH1 L OW0 IH0 NG/
verb
  1. 1

    To surge or roll in billows.

  2. 2

    To swell out or bulge.

noun
  1. 1

    The act of something that billows; a billow.

Source: https://en.wiktionary.org/wiki/billow, https://en.wiktionary.org/wiki/billowing