billow

1 of 3

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 3

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

billowy

3 of 3

adjective

bil·​lowy ˈbi-lə-wē 

sometimes -er/-est

1

: characterized by billows

the billowy sea

2

: suggestive of billows

the billowy prairie

Synonyms of billow

Noun

• wave
• swell

Verb

• protrude
• poke
• bulge

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

Crews with the Los Angeles County Fire Department are battling heavy flames at an Inglewood multi-unit commercial building, as thick smoke billows from a collapsed roof. — Julie Sharp, CBS News, 8 Oct. 2026

Consider that any billow prevention efforts must now apply to the liner rather than the curtain itself. — Bestreviews, Mercury News, 28 Sep. 2026

Verb

Shuting Qiu’s lineup of vivid patterns and billowing silhouettes offered a burst of color and optimism to the city. — Tianwei Zhang, Footwear News, 16 Oct. 2026

Mike Jensen Dobson rushed toward the burning SUV and pulled the man from the vehicle as smoke and fire billowed out. — Jennifer McRae, CBS News, 15 Oct. 2026

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