The short version
Chinese characters are pictographic. Take 口, which is a mouth: an opening with corners. Xu Shen, writing in the second century, defined it as 口，人所以言食也, "what people use to speak and eat." So characters with 口 on the left spend the whole time talking about two things, eating and speaking. 吃 eat, 喝 drink, 咬 bite, 吞 swallow. 说 speak, 喊 shout, 叫 call. That is what one 口 does, and what it stands for.
Two 口
So what about two?
Two mouths side by side make 吅 (xuān). Xu Shen's gloss is 驚嘑也, "a startled cry."
| Character | Pinyin | Meaning | Structure |
|---|---|---|---|
| 哭 | kū | to cry | 吅 + 犬 |
| 骂 | mà | to scold | 吅 + 马 |
| 咒 | zhòu | to curse | 吅 + 几 |
On 哭, opinions differ. Xu Shen said it borrows its sound from 獄 (prison). Duan Yucai, the Qing commentator, rejected that and argued the character is simply 犬 plus 吅, describing a howling dog that was later applied to people. Other scholars have disagreed with Duan.
Three 口
Add one more mouth and you get three. Three of something in Chinese character building usually means "many." 鑫 is three 金, prosperity. 淼 is three 水, a wide expanse of water. 森 is three 木, a forest. So three mouths should mean a lot of people talking. What you get is 品 (pǐn): to taste, to savour; quality; moral character. Xu Shen wrote 品，眾庶也, "the multitude of things." Three mouths comparing rather than arguing. The character turns up in 品味 (taste, refinement) and 品质 (quality).
Four 口
Keep going, and four mouths make 㗊, pronounced jí. Xu Shen's definition: 㗊，眾口也, "many mouths." Rare on its own, and this is what it builds as a component:
| Character | Pinyin | Meaning |
|---|---|---|
| 嚣 | xiāo | clamour, din |
| 噩 | è | shocking, ominous |
| 噪 | zào | noise, racket |
嚣: Xu Shen wrote 聲也。气出頭上。从㗊从頁, sound with breath rising above the head, built from 㗊 (many mouths) plus 頁 (head).
噪 contains a smaller version of the same shape. Its right half is 喿, three mouths on top of 木, a tree. Xu Shen defined 喿 as 鳥羣鳴也, "birds calling in flocks." Add 口 and you get noise in general.
Learn 品 as "taste" and you may as well learn that it is three mouths and three means many. The next 森 or 鑫 you meet, count the repeats. The overlap signals a moderate, appropriate amount.
哭, 嚣, and 噪 carry the same marker. When one of them turns up in reading, the shape is already familiar.
One, two, three, four
Another way to read it, and this is about Chinese thinking more than about character construction. One mouth is basic function. Two mouths are emotion spilling out, which is behind the idiom 百口莫辩, "a hundred mouths cannot argue it away." Three mouths are many people, many voices, and there is a Chinese saying for that too: 三人行必有我师, "among any three people walking together, one can be my teacher." The many here is still a reasonable number. Four mouths have gone past reasonable.
FAQ
Is 口 always a mouth in Chinese characters?
No. In 吃, 喝, 说 it is. In 器 or 舌, reading each 口 as a mouth gets you nowhere.
Why does 品 mean "taste" if it is three mouths?
Three of something usually means "many" in character building. Many mouths means many opinions, and comparing opinions is how quality gets judged. Xu Shen's gloss is 品，眾庶也.
What is the character with four 口?
㗊, jí. Defined as 眾口也, "many mouths." It appears inside 嚣, 噩, and 噪.
Is 哭 a dog with two mouths?
The two mouths are agreed on. The dog is not. Xu Shen said the sound came from 獄; Duan Yucai rejected that and said it was simply 犬 plus 吅.
Can I use this to work out new characters?
Not reliably. It explains characters you already know.
HSK words that contain 口
Every word below has 口 inside it. The first group uses it for what a mouth does. The second group uses it for sounds a mouth makes, which is why so many Chinese question particles and modal words sit under this radical.
The mouth doing its job
The mouth making grammar
Explore characters by sound →Type any pinyin and see every character that shares it. Useful for spotting the components characters have in common.