n. A thin plate, sheet, or layer.n. Botany The expanded area of a leaf or petal; a blade.n. Botany The bladelike part of a kelp.n. A thin layer of bone, membrane, or other tissue.n. Zoology A thin scalelike or platelike structure, as one of the thin layers of sensitive vascular tissue in the hoof of a horse.n. Geology A narrow bed of rock.