saddlebag
noun [ C ] uk/ˈsæd.əl.bæɡ/ us/ˈsæd.əl.bæɡ/
鞍囊，马褡裢；（自行车、摩托车后座的）挂包，工具包
a small bag that you fix to the back of your bicycle saddle, or one of a pair of bags that you put over the back of a horse or over the back wheel of a bicycle or motorcycle