Godan verb with 'ku' ending, Transitive verb
to polish; to shine; to burnish; to scour; to scrub; to brush (teeth); to grind (e.g. a lens)
弟は銀の食器類を磨いた。My brother polished the silver. to refine (a skill, etc.); to improve; to hone; to polish (up); to cultivate (one's character)
Also written 研く【みがく】、琢く【みがく】