The Chinese word for toothpaste is
牙膏

yá gāo

Chinese Definition

toothpaste
1. 牙膏
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
膏
1. fat; grease; oil
2. fatty; oily; rich
3. paste; cream; ointment; poultice
4. sleek; glossy
5. fertile
6. (historical) fatty tissue located at the tip of the heart
7. to moisten; to grease; to lubricate
8. to apply (cream, ointment)
9. to dip a brush in ink