A hard organ in the mouth used for biting and chewing; a tooth (including baby and adult teeth).
毎晩、寝る前に歯を磨くのを忘れないでください。
Don't forget to brush your teeth every night before bed.
子どもの前歯が先週抜けた。
My child's front tooth fell out last week.
虫歯がひどくて、歯医者で治療してもらった。
I had a bad cavity and got it treated by the dentist.
A tooth-like projection on objects such as combs, saws, or gears (a cog or tooth of a saw/combe/gear).
櫛の歯が一本欠けている。
One tooth of the comb is missing.
古いのこぎりは歯が鈍くてよく切れない。
The old saw has dull teeth and doesn't cut well.
歯車の歯が欠けると機械が止まることがある。
If a gear tooth chips, the machine can sometimes stop.
A support or projecting block under a geta (traditional wooden clogs) — a somewhat specialized/older usage.
古い下駄は歯がすり減って歩きにくくなった。
The old geta's supports have worn down and they're hard to walk in.
職人が下駄の歯を新しく作り直した。
The craftsman remade the geta's supports.