A simple pictograph of an open mouth. Mouth, opening, entrance, or a measure word for family members. A square frame shaped like a wide-open mouth.
Picture a mouth stretched open wide, which is why the ancient shape is just a box. That same shape later stretched to mean any opening, like a doorway or entrance. It also sits on the left side of mouth-related characters like 吃, 喝, and 叫.
口 is the formal, written mouth. In everyday speech about your own body, people say 嘴 or use the set phrase 口渴.
For a building entrance you need the full word 门口, not bare 口. 学校口 sounds like a cut-off robot phrase.
口 counts mouthfuls, not whole objects. A whole apple is 一个苹果, not 一口苹果.
Say 我嘴很干 or 我口渴. 口 is the formal written mouth, not your everyday face mouth.
口 and 嘴 both mean 'mouth', but they live in different worlds. 口 shows up in written words, signs, and set phrases. 嘴 is the physical mouth you point at — the one that gets dry, full, or talks too much. Using 口 about your own body sounds like a medical textbook.
| Dimension | Natural | Avoid |
|---|---|---|
| Everyday speech | 我嘴很干 / 我口渴 | 我口很干 |
| Written / compounds | 人口, 门口, 出口 | 人嘴, 嘴语 |
| Talking about a person | 他嘴很甜 | 他口很甜 |
口 also means 'opening,' so 门口 is the door's opening, not a door's mouth.
口 started as a picture of a mouth, then stretched to mean any opening or entrance. So 门口 is the opening at the door. 入口 is the opening you go in. 出口 is the opening you go out. Once you see 口 as 'opening', a whole family of words clicks into place.
| Dimension | Natural | Avoid |
|---|---|---|
| Building entrance | 学校门口 | 学校口 |
| Airport signs | 入口 / 出口 | 进门 / 出门 (as signs) |
| Meaning of 口 | opening, entrance | only 'mouth' |
Yes: 口 counts mouthfuls and family members, like 一口水 or 五口人.
口 works as a measure word for anything that goes in by the mouthful: 一口米饭, 一口水. It also counts people in a family: 我家有五口人. Just don't use it for whole objects — a whole apple is 一个苹果, not 一口苹果.
| Dimension | Natural | Avoid |
|---|---|---|
| A sip / bite | 喝一口水, 吃一口饭 | 喝一个水 |
| Counting family | 五口人 | 五个口人 |
| Whole object | 一个苹果 | 一口苹果 |
This heartwarming story reveals the quiet devotion of a father. As you read, notice the repeated actions and how a simple cup of tea becomes meaningful.
老先生坐在七号桌子前，喝了第一 口 热茶。
A young man helps an old man look for his cat. But the real surprise is why the old man wanted to find the cat. Read on to learn about kindness and friendship.
一天，白天明在学校 大门口 前边看见有人写了找猫的话：“我想找一只大白猫。
Before you read, close your eyes and imagine a rainy afternoon. This story uses simple HSK 1 words to show how rain can become a talking friend.
我坐在 门口 ，看雨。
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