층
cheung · TOPIK 1
floor, story (of a building)
🏢 From hanja 層 (layer): a building is layers stacked up, each one a 층
층 comes from the hanja 層, meaning layer or stratum. A floor is just one layer of a building, so 3층 is the third layer up. The same 層 gives Chinese céng and Japanese sō, both also used for layers and storeys.