godan verb (-mu), transitive verb
polish thoroughly; rub to a shine
Implies careful, repeated polishing until a deep luster is achieved. Often used for shoes, metal, or surfaces.
彼は毎朝、靴を磨き込んでから出かける。
He polishes his shoes thoroughly every morning before going out.
職人が包丁を磨き込
When the craftsman polished the knife thoroughly, the blade shone like a mirror.