From 登(のぼ)り (nobori, “climbing, 連(れん)用(よう)形(けい) (ren'yōkei, “stem or continuative form”) of the verb 登(のぼ)る (noboru, “to climb”).”) + 棒(ぼう) (bō, “pole”).
のぼりぼう • (nobori-bō)