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

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Etymology

Origin of foam

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

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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

It all started back in 2010 with the introduction of the Hoka line of max-cushion shoes, which led other brands to develop similar styles, each stacked with its own patented lightweight foam.

From The Wall Street Journal ● Oct. 10, 2026

The Surge has pulled its giant foam finger saying “DEBATES” out of storage, because friends, it is debate season.

From Slate ● Oct. 10, 2026

The EA is also investigating another incident nearby at Brislington Brook, where dead fish and eels, foam on the water and "an intense chemical smell" were reported by volunteers.

From BBC ● Sep. 28, 2026

Some stores had empty shelves over the weekend as residents raced to buy essentials, while fresh produce at market stalls was kept dry in polystyrene foam boxes or hanging just above the water level.

From Barron's ● Sep. 27, 2026

Finally, after threading her way through a cluster of rocks surrounded by foam, she came again to an endless stretch of water.

From "A Girl Named Disaster" by Nancy Farmer

They engineered carefully controlled porous materials that imitate the way natural foams scatter light while also drawing inspiration from water-repellent surfaces found on leaves and flower petals.

From Science Daily ● Sep. 10, 2026

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

Since then, high-tech foams have been perfected to return more energy to the runner than ever and come in lighter than previous materials.

From The Wall Street Journal ● Apr. 26, 2026

His mouth foams; he shakes her with all his own shock and indignation.

From "What the Night Sings" by Vesper Stamper

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

While the barista at Hurricane Coffee Co. foamed the oat milk for my lavender latte, I wondered which ingredient would tag my neurotransmitters first: the stimulating caffeine or the soothing lavender.

From Washington Post ● Jul. 22, 2022

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

From BBC ● Feb. 10, 2022

Together they plunged over a fall of green-hued stone, and foamed down into a dell.

From "The Fellowship of the Ring" by J.R.R. Tolkien

It helps nurture a slower, older way of life, with pocket flocks and modest dairy herds enclosed by thick hedgerows foaming with cow parsley and twittering songbirds.

From The Wall Street Journal ● Apr. 11, 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

Hernandez told police she found her baby foaming at the mouth and having an apparent seizure after emerging from her procedure at Always Beautiful Medical Spa, according to the police report.

From Los Angeles Times ● Jul. 9, 2025

Symptoms of muscarine poisoning include muscle cramps, blurred vision, foaming from the mouth, vomiting and diarrhea.

From Salon ● Feb. 20, 2025

There was a white crust around the broad crescent of its mouth, and when it opened its jaws to roar again, something wet, white, and foaming dripped from its pointed teeth.

From "Six of Crows" by Leigh Bardugo

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Related Words

• cream
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