foam
n. uncountablen. a mass of small bubbles that forms on top of a liquid. You see this on coffee, in the bath, or on ocean waves.
n. a mass of small bubbles formed on or in liquid, typically by agitation, fermentation, or chemical reaction. Often used in literary contexts to describe the sea or the froth on waves.
The waves left white foam on the sand.
The barista carefully poured the steamed milk to create a thick layer of foam on the latte.
In the poet's description, the churning sea was a wild expanse of white foam and dark water, crashing relentlessly against the jagged cliffs.
From Middle English fom, foom, from Old English fām, from Proto-West Germanic faim, from Proto-Germanic faimaz, from Proto-Indo-European (s)poHy-m-os, from (s)poH(y)- (“foam”). Cognate with German Feim (“foam”), Latin spūma (“foam”), Latin pūmex (“pumice”), Sanskrit फेन (phéna, “foam”), possibly Northern Kurdish fê (“epilepsy”).
Uncountable when referring to the substance in general; occasionally countable when referring to specific types of industrial or chemical foam.