The Chinese word for mouth is
嘴

zuǐ

Chinese Definition

嘴
1. (anatomy) mouth (especially the part of the face associated with the mouth)
2. (figurative) mouth-like object; beak; nozzle; spout (of a teapot, etc.)
3. (figurative) food
4. (figurative) utterance; spoken words; speech
5. (Cantonese) to kiss
不敢嘴人
6. (literary) beak

口
1. (anatomy) mouth, especially the lips and internal mouth cavity
漱漱你的口。 (Shù shù nǐ de kǒu.) - Rinse your mouth out.
這話出自你的口，聽來令人奇怪。 (Zhè huà chūzì nǐ de kǒu, tīnglái lìngrén qíguài.) - This sounds strange in your mouth.
2. entrance; opening; mouth (of an object)
入口 (rùkǒu) - entrance
出口 (chūkǒu) - exit
門口 (ménkǒu) - doorway
3. gateway
^張家口 (Zhāngjiākǒu) - Zhangjiakou
^口北 (Kǒuběi) - the area beyond the Great Wall
口蘑 (kǒumó) - St. George's mushroom (Calocybe gambosa)
4. hole; cut
口子zi (kǒuzi) - hole
傷口 (shāngkǒu) - wound
5. port
電腦端口 (shāngkǒu) - computer port
Csēi口 (sēikǒu) - USB-C port
6. perimeter
人口 (rénkǒu) - population
戶口 (hùkǒu) - hukou
7. government organ; department
三口之家 (sān kǒu zhī jiā) - a family of three
我可以吃一口嗎？ (Wǒ kěyǐ chī yī kǒu ma?) - Can I have a bite?
8. (neologism, slang) to fellate
9. Variant of 名