The word "whitecaps" is a transparent English compound formed from two native elements. "White," a fundamental color term of Germanic origin, has remained remarkably stable in meaning from its Proto-Indo-European root ḱweyt- (to shine). "Cap," entering English from Latin via Old French, originally denoted a head covering. By the 17th century, "cap" was applied figuratively to anything that sits on top, like a mountain cap or, in this case, the frothy crest of a breaking wave. The compound "whitecaps" thus logically and visually describes the wind-whipped waves as if they are wearing white, foamy crowns, a vivid example of descriptive nautical terminology.

Structure: white (color) + caps (coverings) - white: From Old English hwīt, meaning "bright, radiant, clear." In this compound, it describes the color of the foam. - caps: From the noun cap, from Late Latin cappa (a head-covering). In this compound, it functions metaphorically to mean the crests or tops of the waves.