/ˈleɪə(r) ||; ˈleɚ/noun [C] a thickness or quantity of sth that is on sth else or between other things （物质的）一层:
A thin layer of dust covered everything in the room. 房间里的东西全都盖上一层薄薄的尘埃。It's very cold. You'll need several layers of clothing. 天气很冷，你要多穿几件衣服。the top/bottom layer 顶╱底层the inner/outer layer 里╱外层