the.com/sponge cake

means A light cake made with little or no fat, where whipped eggs trap air that the batter holds onto as it bakes, giving it that springy, spongy crumb.

from Named simply for its resemblance to a sea sponge — the open, airy, pitted texture created by all those egg-whipped bubbles. The technique and name trace back to at least the 18th century, when cooks discovered that beaten eggs alone, without added leavening, could lift a batter into something impossibly light. No exotic word-history here — just a cake that looked like a sponge and got called one.