The Chinese word for toothbrush is
牙刷

yá shuā

Chinese Definition

toothbrush
1. 名词. 牙刷
Components
牙
1. (anatomy) tooth
拔牙 - to take out a tooth -
我牙疼。 - I have a toothache. -
2. (anatomy) ivory; tusk of elephant
牙雕 - ivory sculpture -
3. screw thread
4. (literary, obsolete) to bite
5. (obsolete) Alternative form of 衙 (government office; yamen)
6. (obsolete) Alternative form of 芽 (to sprout)
7. (Hong Kong Cantonese, Internet slang) (Prefix used in front of the surname or last character of someone’s given name to express familiarity or friendliness.)
8. (historical) broker
刷
1. brush (tool)
2. to brush; to scrub; to clean with a brush
3. to paint with a brush
4. (colloquial) to eliminate
5. (chiefly Mainland neologism colloquial) to browse through (updates on social media etc.); to flip through
刷手機 - to check one's phone (for updates on social media etc.)
這部電視劇太好看了！我已經開始四刷了！ - This television drama is so good! I have already begun to watch through it for the fourth time!
6. (colloquial) to write; to finish (a massive quantity of works)
7. (video games, transitive) to grind
刷錢 - to grind for in-game money
8. (video games) to spawn
刷車器 - car spawner
9. (dialectal) to pick; to choose