剑桥词典a first layer of paint that is put on a surface in order to improve the appearance of the final one, or the paint used for this 內塗層，底塗層；底漆，底層塗料 Those red walls will probably need two undercoats. 那些紅色牆壁可能需要刷兩層底漆。 比較topcoat 返回 undercoat