<p><strong>Noun</strong></p><ul><li>a great wave or surge of the sea.</li><li>Synonyms: whitecap, roller, comber, breaker, swell.</li><li>any surging mass: billows of smoke.</li></ul><p><strong>Verb</strong></p><ul><li>(used without object) to rise or roll in or like billows; surge.</li><li>to swell out, puff up, etc., as by the action of wind: flags billowing in the breeze.</li><li>(used with object) to make rise, surge, swell, or the like: A sudden wind billowed the tent alarmingly.</li></ul>