Web拱. arch uk / ɑːtʃ/ us / ɑːrtʃ/ C2 noun. a structure, consisting of a curved top on two supports, that holds the weight of something above it: In many churches the side aisles are separated from the central aisle by a row of arches. 很多教堂中,侧廊与主廊之间都有一排拱门相隔。.