1mouth
2classifier for bites or mouthfuls
3classifier for things with mouths (people, domestic animals, cannons, wells etc)
Examples
wǒ men我们jiā家yǒu有wǔ五kǒu口rén人。
我们家有五口人。
Our family consists of five members.
你家有几口人？
How many people are there in your family?
我妈妈留了口信给我。
My mother left me a message.