From 待(ま)ち (machi, “連(れん)用(よう)形(けい) (ren'yōkei, “stem or continuative form”) of the verb 待(ま)つ (matsu).”) + 惚(ぼう)け (bōke).
まちぼうけ • (machibōke) ←まちぼうけ (matibouke)?