牙刷
yá shuā · HSK 4
toothbrush
🪥 牙刷 = tooth + brush
牙 means tooth and 刷 means brush, so 牙刷 is literally tooth-brush. The classifier 把 (bǎ) is used for handled objects you grip.
牙 — pictograph of interlocking molars/tusks
牙 originated as a pictograph of two interlocking teeth or animal tusks, showing the upper and lower jaws meshing together. Originally it referred specifically to molars or fangs (as opposed to 齒, the front teeth), and by extension came to mean tusks and ivory. In modern Chinese it is the general word for 'tooth.'
刷 — 刂 knife + 㕞 (brush, phonetic)
A semantic-phonetic compound. The right side 㕞 originally depicted a brush or scrubber and supplies the sound, while the knife radical 刂 hints at scraping or sweeping action. The character came to mean 'to brush, scrub, or swipe,' later extending to modern senses like swiping a card or binge-watching.