billow

1 of 2

noun

bil·​low ˈbi-(ˌ)lō 

1

: wave

especially : a great wave or surge of water

the rolling billows of the sea

2

: a rolling mass (as of flame or smoke) that resembles a high wave

Billows of smoke poured out of the building.

billows of fog

billowy

ˈbi-lə-wē 

adjective

billow

2 of 2

verb

billowed; billowing; billows

intransitive verb

1

: to rise or roll in waves or surges

the billowing sea

2

: to bulge or swell out (as through action of the wind)

billowing clouds

… the flags … billowed out in pride …

—G. B. Oxnam

transitive verb

: to cause to billow

a field of burning grass billowing thick black clouds of smoke into the sky

—Donald Windham

Synonyms

Noun

• surge
• swell
• wave

Verb

• bag
• balloon
• beetle
• belly
• bulge
• bunch
• jut
• overhang
• poke
• pooch [chiefly dialect]
• pouch
• pout
• project
• protrude
• stand out
• start
• stick out
• swell

Examples of billow in a Sentence

Noun

Billows of smoke poured out of the burning building.

the rolling billows of the sea

Verb

the curtains in the open windows billowed in the summer wind

Recent Examples on the Web

Noun

In the distance, near the business park, demonstrators were setting off fireworks and a billow of black smoke could be seen. —Rachel Uranga, Los Angeles Times, 8 June 2025

Black smoke billows after a pair of inconclusive votes, while white smoke will immediately billow if a new pontiff is chosen. —Katie Primm, NBC news, 9 May 2025

Verb

Israelis seek shelter as Iran retaliates Sirens blared throughout Tel Aviv late Friday and smoke billowed in the sky as people ran for shelter as Iran fired hundreds of missiles at Israel in retaliatory strikes, which continued into Saturday morning. —Rebecca Rosman, NPR, 14 June 2025

Natanz nuclear-enrichment complex Social media footage verified by The Times, as well as an Iranian news report, show flames and thick black smoke billowing from the Natanz nuclear-enrichment complex. —Martín González Gómez, New York Times, 13 June 2025

Word History

Etymology

Noun and Verb

Old Norse bylgja; akin to Old High German balg bag — more at belly

First Known Use

Noun

1552, in the meaning defined at sense 1

Verb

1592, in the meaning defined at intransitive sense 1

Rhymes for billow

• pillow
• armadillo
• caudillo

Kids Definition

billow

1 of 2 noun

bil·​low ˈbil-ō 

1

: wave entry 2 sense 1

especially : a large wave

2

: a rolling mass like a high wave

billows of smoke

billow

2 of 2 verb

1

: to rise or roll in waves

the billowing ocean

2

: to bulge or swell out

sails billowing in the breeze