siding

1. N-UNCOUNT Siding is a wooden, plastic, or metal covering on the outside walls of a building. (建筑外墙木制、塑料制或金属制的)壁板[美国英语]

2. N-COUNT A siding is a short railway track beside the main tracks, where engines and cars are left when they are not being used. (铁路线的)侧线