foam

American  

[fohm] / foʊm /

noun

1. a collection of minute bubbles formed on the surface of a liquid by agitation, fermentation, etc..

   foam on a glass of beer.

   Synonyms:

   scum, fizz, head, spume, froth

2. the froth of perspiration, caused by great exertion, formed on the skin of a horse or other animal.

3. froth formed from saliva in the mouth, as in epilepsy and rabies.

4. a thick frothy substance, as shaving cream.

5. (in firefighting)

   1. a chemically produced substance that smothers the flames on a burning liquid by forming a layer of minute, stable, heat-resistant bubbles on the liquid's surface.

   2. the layer of bubbles so formed.

6. a dispersion of gas bubbles in a solid, as foam glass, foam rubber, polyfoam, or foamed metal.

7. Literary. the sea.

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verb (used without object)

• foams,
  present (3rd person singular)
• foamed,
  past participle,  past
• foaming
  present participle

1. to form or gather foam; emit foam; froth.

verb (used with object)

• foams,
  present (3rd person singular)
• foamed,
  past participle,  past
• foaming
  present participle

1. to cause to foam.

2. to cover with foam; apply foam to.

   to foam a runway before an emergency landing.

3. to insulate with foam.

4. to make (plastic, metal, etc.) into a foam.

idioms

1. foam at the mouth, to be extremely or uncontrollably angry.

foam British  

/ fəʊm /

noun

1. a mass of small bubbles of gas formed on the surface of a liquid, such as the froth produced by agitating a solution of soap or detergent in water

2. frothy saliva sometimes formed in and expelled from the mouth, as in rabies

3. the frothy sweat of a horse or similar animal

4. 1. any of a number of light cellular solids made by creating bubbles of gas in the liquid material and solidifying it: used as insulators and in packaging

   2. ( as modifier )

      foam rubber

      foam plastic

5. a colloid consisting of a gas suspended in a liquid

6. a mixture of chemicals sprayed from a fire extinguisher onto a burning substance to create a stable layer of bubbles which smothers the flames

7. a poetic word for the sea

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verb

1. to produce or cause to produce foam; froth

2. (intr) to be very angry (esp in the phrase foam at the mouth )

foam Scientific  

/ fōm /

1. Small, frothy bubbles formed in or on the surface of a liquid, as from fermentation or shaking.

2. A colloid in which particles of a gas are dispersed throughout a liquid.

3. Compare aerosol emulsion

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Other Word Forms

Derived Forms

• foamer
  noun
• defoam
  verb (used with object)
• foamable
  adjective
• foamless
  adjective
• foamlike
  adjective
• unfoamed
  adjective
• unfoaming
  adjective
• foamingly
  adverb

Inflected Forms

Participles

• foaming
  present
• foamed
  past

Conjugated Forms

Present

• foam
  simple
• foams
  simple
• have foamed
  perfect
• has foamed
  perfect
• am foaming
  progressive
• are foaming
  progressive
• is foaming
  progressive
• have been foaming
  perfect progressive
• has been foaming
  perfect progressive

Past

• foamed
  simple
• had foamed
  perfect
• was foaming
  progressive
• were foaming
  progressive
• had been foaming
  perfect progressive

Future

• will foam
  simple
• will have foamed
  perfect
• will be foaming
  progressive
• will have been foaming
  perfect progressive

Etymology

Origin of foam

before 900; Middle English fom, Old English fām; cognate with German Feim

Explanation

Foam is a substance with so many tiny air bubbles that it becomes frothy or thick. Your liquid shampoo becomes a foam as you lather it into your wet hair. There's a layer of foam on top of your root beer float, and shaving cream usually comes out of its can in the form of foam. When something froths up this way, you can say that it foams, like turbulent ocean water or a bubble bath that grows as you add water to the tub. The Old English root word is fam, which means "foam," but also "saliva froth" and "sea."

Example Sentences

See Examples For:

foam foams foamed foaming

Struggling with bloated inventory and slowing sales a year ago, Crocs could have been tempted to slash prices to start moving as many of its foam clogs out the door as possible.

From The Wall Street Journal ● Aug. 24, 2026

Then comes a bevy of scientific instruments, a small nuclear engine, and shiny orange foam to keep the instruments warm in space.

From Los Angeles Times ● Aug. 22, 2026

The property also features a sizable media room, an expansive primary suite—with his-and-her closets and a spalike bathroom—and a playroom with its own stage and foam pit.

From MarketWatch ● Aug. 18, 2026

You can then progress to standing on a folded towel or foam pad.

From Science Daily ● Aug. 16, 2026

She waved back, but didn’t smile as she sipped from a foam cup.

From "Ivy Aberdeen’s Letter to the World" by Ashley Herring Blake

The "infinite personalisation" through foams, flavours, and protein are "almost pure profit" for the chain.

From BBC ● Aug. 29, 2026

The three movements include “an invocation to hands that weave”; “a meeting of foams, needles, songs, threats and pulsations”; and what Negrón calls “an archipelago of resonances and possibilities.”

From Los Angeles Times ● Jun. 3, 2026

One of the chemicals found by both the EA and the independent testing is PFOS, a substance banned in the UK due to potential carcinogenic risks, often used in firefighting foams.

From BBC ● May 20, 2026

Researchers at Tokyo Metropolitan University have uncovered the real reason liquid drains from foams, resolving a long-standing scientific puzzle.

From Science Daily ● Mar. 23, 2026

Spring fog foams over the ramparts of the newly opened Belle Isle Bridge.

From "Middlesex: A Novel" by Jeffrey Eugenides

The straw made from foamed CDA was a prototype to see if increasing the surface area would accelerate break down.

From Science Daily ● Jan. 30, 2024

Pennsylvania officials will use 2,000 tons of lightweight foamed glass nuggets to fill in the section of a U.S.

From Washington Times ● Jun. 15, 2023

Visible through a tangle of sea-grape trees, swells gently foamed over the inshore reefs.

From Washington Post ● Apr. 29, 2022

Since then, Queensland has been using a process called foamed bitumen stabilisation.

From BBC ● Feb. 10, 2022

His eyes flashed and his teeth flashed and his jaws foamed.

From "Norse Mythology" by Neil Gaiman

“There are contestants that become very polarizing and you’ll have people absolutely foaming at the mouth wanting them to lose,” says former champion Mattea Roach, speaking from experience.

From The Wall Street Journal ● Apr. 21, 2026

She calmly described how her mum had been foaming at the mouth and shaking, and clearly gave their address when asked, LAS said.

From BBC ● Apr. 10, 2026

Hernandez told police she returned at 4:30 p.m. and found her 1-year-old foaming at the mouth in the midst of a seizure, according to the police report.

From Los Angeles Times ● Feb. 17, 2026

The A12 cafe, on one of the busiest avenues in the capital, displays a large picture of a foaming pint on its window.

From Barron's ● Nov. 19, 2025

But the longer he stared at that water, that foaming green water, rising higher every second, the more certain he became: The Titanic was in trouble.

From "I Survived the Sinking of the Titanic, 1912" by Lauren Tarshis

Related Words

• cream
• froth
• spray