How to say "tooth" in Japanese

• 歯はJLPT N5approx.Common
  nounThe everyday word for the teeth in your mouth, whether a single tooth or all of them. Think of brushing your teeth, a toothache, or a trip to the dentist.
  その赤あかちゃんは歯はが生はえはじめている。↗

  The baby is cutting his teeth.
• 歯し
  nounThe same character in its on-reading. On its own it is not how you refer to a tooth; it appears almost only inside compound words, so 歯（は） is the word you want.
• トゥース
  nounThe English word 'tooth' written in katakana. It is seldom the word you want for the meaning itself: it turns up mostly in product names, advertising and other English-flavoured contexts, not in ordinary sentences.

For the body part, 歯（は） is the everyday word, covering both 'tooth' and 'teeth'; 歯（し） is the same character's on-reading, met almost entirely inside compounds, while 「トゥース」 is the English loanword, mostly in product names and advertising.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 歯はtooth
• 歯しtooth
• トゥースtooth
• めtooth (of a saw, comb, etc.)