- a great wave or surge of the sea.
- any surging mass: billows of smoke.
verb (used without object)
- to rise or roll in or like billows; surge.
- to swell out, puff up, etc., as by the action of wind: flags billowing in the breeze.
verb (used with object)
- to make rise, surge, swell, or the like: A sudden wind billowed the tent alarmingly.
- a large sea wave
- a swelling or surging mass, as of smoke or sound
- a large atmospheric wave, usually in the lee of a hill
- (plural) poetic the sea itself
- to rise up, swell out, or cause to rise up or swell out
1550s, perhaps older in dialectal use, from Old Norse bylgja “a wave, a billow,” from Proto-Germanic *bulgjan (cf. Middle High German bulge “billow, bag”), from PIE *bhelgh- “to swell” (see belly (n.)).
1590s, from billow (n.). Related: Billowed; billowing.