foam

/foʊm/

/fəʊm/

Other forms: foaming; foamed; foams

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."

Definitions of foam

1. noun

   a mass of small bubbles formed in or on a liquid
   synonyms: froth

   types:

   shaving foam

   toiletry consisting of a liquid preparation containing many small bubbles that soften the beard before shaving

   head

   the foam or froth that accumulates at the top when you pour an effervescent liquid into a container

   lather

   the foam resulting from excessive sweating (as on a horse)

   lather, soapsuds, suds

   the froth produced by soaps or detergents

   spume

   foam or froth on the sea

   white water, whitewater

   frothy water as in rapids or waterfalls

   shaving cream, shaving soap

   toiletry consisting of a preparation of soap and fatty acids that forms a rich lather for softening the beard before shaving

   type of:

   bubble

   a hollow globule of gas (e.g., air or carbon dioxide)
2. noun

   a lightweight material in cellular form; made by introducing gas bubbles during manufacture
   types:

   Styrofoam

   a light resilient foam of polystyrene

   foam rubber

   spongy rubber; made by introducing air bubbles before vulcanization and used for cushioning or upholstery

   type of:

   material, stuff

   the tangible substance that goes into the makeup of a physical object
3. verb

   become bubbly or frothy or foaming
   “The river was foaming”

   synonyms: effervesce, fizz, form bubbles, froth, sparkle

   types:

   lather

   form a lather

   seethe

   foam as if boiling

   type of:

   bubble

   form, produce, or emit bubbles