foam, froth (noun)

a mass of small bubbles formed in or on a liquid

"the beer had a thick head of foam"

foam (verb)

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

foam, froth, fizz, effervesce, sparkle, form bubbles (verb)

become bubbly or frothy or foaming

"The boiling soup was frothing"; "The river was foaming"; "Sparkling water"

foam (Noun)

A substance composed of a large collection of bubbles or their solidified remains.

foam (Noun)

sea foam; the sea.

foam (Verb)

To form or emit foam.

Foam

A foam is a substance that is formed by trapping pockets of gas in a liquid or solid. A bath sponge and the head on a glass of beer are examples of foams. In most foams, the volume of gas is large, with thin films of liquid or solid separating the regions of gas. An important division of solid foams is into closed-cell foams and open-cell foams. In a closed-cell foam, the gas forms discrete pockets, each completely surrounded by the solid material. In an open-cell foam, the gas pockets connect with each other. A bath sponge is an example of an open-cell foam: water can easily flow through the entire structure, displacing the air. A camping mat is an example of a closed-cell foam: the gas pockets are sealed from each other, and so the mat cannot soak up water. Foams are examples of dispersed media. In general, gas is present in large amount so it will be divided in gas bubbles of many different sizes separated by liquid regions which may form films, thinner and thinner when the liquid phase is drained out of the system films. When the principal scale is small, i.e. for a very fine foam, this dispersed medium can be considered as a type of colloid. The term foam may also refer to anything that is analogous to such a foam, such as quantum foam, polyurethane foam, XPS foam, Polystyrene, phenolic, or many other manufactured foams.