磨く
みがく · migaku · JLPT N5 · verb-godan
to brush
🪥✨ mi-ga-ku: ME GAwk at my teeth after brushing till they shine
Sound hook: mi-ga-ku ≈ me gawk. You brush or polish something until it is worth gawking at. The kanji 磨 holds 石 (stone) under 麻: rubbing against stone is how things were ground smooth, so the same verb covers teeth, shoes and skills.
磨 — stone 石 + hemp 麻 (phonetic)
A semantic-phonetic compound: 石 'stone' gives the meaning (grinding involves stones), while 麻 'hemp' supplies the sound. Originally referred to a millstone or the act of grinding grain, later extending to 'rub, polish, wear down' and figuratively 'to torment' or 'waste time'.