swell

American  

[swel] / swɛl /

verb (used without object)

swelled, swollen, swelled, swelling

1. to grow in bulk, as by the absorption of moisture or the processes of growth.

   Synonyms:

   expand, distend

   Antonyms:

   contract

2. Pathology. to increase abnormally in size, as by inflation, distention, accumulation of fluids, or the like.

   Her ankles swelled from standing.

3. to rise in waves, as the sea.

4. to well up, as a spring or as tears.

5. to bulge out, as a sail or the middle of a cask.

   Synonyms:

   protrude

6. to grow in amount, degree, force, etc.

7. to increase gradually in volume or intensity, as sound.

   The music swelled.

8. to arise and grow within one, as a feeling or emotion.

9. to become puffed up with pride.

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verb (used with object)

swelled, swollen, swelled, swelling

1. to cause to grow in bulk.

   Synonyms:

   expand, inflate

2. to cause to increase gradually in loudness.

   to swell a musical tone.

3. to cause (a thing) to bulge out or be protuberant.

4. to increase in amount, degree, force, etc.

   Antonyms:

   diminish, decrease

5. to affect with a strong, expansive emotion.

6. to puff up with pride.

noun

1. the act of swelling or the condition of being swollen.

2. inflation or distention.

   Synonyms:

   swelling

3. a protuberant part.

   Synonyms:

   bulge

4. a wave, especially when long and unbroken, or a series of such waves.

   Synonyms:

   billow

5. a gradually rising elevation of the land.

6. an increase in amount, degree, force, etc.

7. a gradual increase in loudness of sound.

8. Music.

   1. a gradual increase (crescendo) followed by a gradual decrease (diminuendo) in loudness or force of musical sound.

   2. the sign (< >) for indicating this.

   3. a device, as in an organ, by which the loudness of tones may be varied.

9. a swelling of emotion within one.

10. Slang.

    1. a fashionably dressed person; dandy.

    2. a socially prominent person.

adjective

Informal.

1. (of things) stylish; elegant.

   a swell hotel.

2. (of persons) fashionably dressed or socially prominent.

   Synonyms:

   grand

3. first-rate; fine.

   a swell party.

   Synonyms:

   grand

swell British  

/ swɛl /

verb

1. to grow or cause to grow in size, esp as a result of internal pressure Compare contract contract

2. to expand or cause to expand at a particular point or above the surrounding level; protrude

3. to grow or cause to grow in size, amount, intensity, or degree

   the party is swelling with new recruits

4. to puff or be puffed up with pride or another emotion

5. (intr) (of seas or lakes) to rise in waves

6. (intr) to well up or overflow

7. (tr) to make (a musical phrase) increase gradually in volume and then diminish

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noun

1. 1. the undulating movement of the surface of the open sea

   2. a succession of waves or a single large wave

2. a swelling or being swollen; expansion

3. an increase in quantity or degree; inflation

4. a bulge; protuberance

5. a gentle hill

6. informal a person very fashionably dressed

7. informal a man of high social or political standing

8. music a crescendo followed by an immediate diminuendo

9. Also called: swell organ.  music

   1. a set of pipes on an organ housed in a box ( swell box ) fitted with a shutter operated by a pedal, which can be opened or closed to control the volume

   2. the manual on an organ controlling this Compare choir great

adjective

1. informal stylish or grand

2. slang excellent; first-class

Other Word Forms

• reswell verb
• underswell verb (used without object)
• unswelled adjective

Etymology

Origin of swell

First recorded before 900; Middle English swellen (verb), Old English swellan; cognate with Dutch zwellen, German schwellen, Old Norse svella; akin to Gothic ufswalleins “pride”

Explanation

To swell is to expand or grow larger. If your brother's face started to swell after he ate lobster for the first time, you'd probably guess that he's allergic to shellfish. You can use the word swell to describe what happens to an injured body part, like a black eye that swells up, or in a figurative way, to describe a feeling of fullness, like when your heart swells with pride at your sister's big music performance. In the 1930s, swell became a popular slang term meaning "great" or "excellent." But it also can describe a wealthy, elegant person, like a group of swells at a fancy restaurant.

Example Sentences

Wolves have seen their population swell in Europe in recent years, with the European Union reporting a 35% increase to 23,000 from 2016 to 2023, concentrated especially in Central Europe and Alpine regions.

From BBC • Apr. 24, 2026

Nearly every nontraded BDC saw March-quarter redemption requests swell above the 5% of net assets that managers prepare for.

From Barron's • Apr. 24, 2026

But unlike the megahits “Cats” and “Phantom of the Opera,” “Chess” was checkmated shortly after it arrived in New York in a swell of London fanfare.

From Los Angeles Times • Apr. 22, 2026

The missile makers are making upfront investments to boost output, but the moves could swell profits if the government makes good on its promised contracts over the coming years.

From The Wall Street Journal • Apr. 16, 2026

All the while, my father continued to swell.

From "Becoming" by Michelle Obama

Related Words

• accumulate
• add to
• balloon
• bloat
• bulge
• enlarge
• expand
• fatten
• grow
• increase
• mount
• rise
• surge