What does billow mean?
A billow is a great wave — originally specifically a large wave on the sea, and by extension any broad, swelling mass of something in motion, such as smoke, clouds, dust, or fabric. It also functions as a verb meaning to swell out or surge in this way: sails billow in the wind, smoke billows from a chimney, and skirts billow as someone turns. The word comes from Old Norse bylgja, meaning 'wave', and entered English in the medieval period. Today its literal nautical sense survives mainly in literary contexts, while the extended uses are firmly established in ordinary speech and writing. Billow carries a dramatic, visually rich connotation, evoking largeness, power, and graceful, rolling movement, which makes it a favorite of novelists, poets, and journalists describing fires, storms, and sweeping motion. Its derived forms include the adjective billowy and the participles billowed and billowing.
A great wave of the sea; more broadly, a large swelling or surging mass of something such as smoke, cloud, or cloth.
"Great billows crashed against the cliff as the storm intensified."
The literal 'sea wave' sense now appears mostly in literary or historical writing; the extended sense ('billows of smoke') is current and common.
To swell out or fill with air like a wave, or to rise and move in large rolling masses.
"The curtains billowed gently in the evening breeze."
Usually used in the plural when referring figuratively to masses of smoke, cloud, or fabric; the singular appears mainly in literary descriptions of waves.
"Billows of white steam poured from the locomotive's funnel."
Before it ever described smoke or curtains, a billow was simply a giant ocean wave — the word sailed straight out of Old Norse into English.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of billow
Billow derives from the Old Norse bylgja, meaning 'wave', and was adopted into English during the Middle Ages, likely through contact with Scandinavian settlers. Its earliest recorded senses referred directly to great waves of the sea. Over time the word widened to describe any large swelling or surging mass, such as smoke or clouds, and developed into a verb describing that same rolling, swelling motion. Modern Scandinavian languages preserve closely related forms, including Swedish bölja and Danish bølge.
Related word forms
How billow is actually used
In modern usage the noun sense of 'sea wave' is somewhat literary, while the verb and the figurative noun ('billows of smoke') are common in both everyday and descriptive writing. The word carries a vivid, slightly poetic connotation of grandeur or drama in movement.
Easily confused with billow
"Below" means at a lower position or level, while "billow" refers to a large wave or a swelling, surging motion.
A pillow is a cushion for the head, whereas a billow is a wave or swelling mass; they differ only by one letter but share no meaning.