What is a wave that breaks into foam called?

A wave that breaks into foam is referred to as a breaker. This term specifically describes the process where a wave, upon reaching shallow water, becomes unstable and collapses, causing it to break and create foam on the water’s surface. This phenomenon occurs due to the wave's energy becoming concentrated as the water depth decreases, leading to the wave cresting over and producing the characteristic churning foam that is often seen on beaches.

Surge refers to a general increase in wave height and does not specifically imply the formation of foam. Breakwater is a structure designed to protect against wave action, but it is not a description of a breaking wave itself. Swells refer to long-period waves that are typically smooth and do not break; they are associated with open ocean conditions rather than the turbulent, foamy conditions created by breaking waves. Hence, the definition of a breaker aligns perfectly with the question, as it encompasses the physical characteristics of a wave that results in the creation of foam.