口 — Mouth, Opening, Entrance

Meaning

The kanji 口 (kuchi) is a fundamental character in Japanese, primarily meaning "mouth" or "opening." Its meaning is straightforward and visually intuitive. As a pictograph, this character offers an excellent example. It originated from an ancient drawing depicting the shape of an open mouth. Over centuries, its form, like many kanji, was simplified and stylized, eventually evolving into the familiar square shape we see today. Even with this simplification, the link between the square shape and the concept of a mouth or opening remains clear and easy to grasp.

Beyond just the anatomical mouth, 口 also refers to various other types of openings. Think of an entrance, an exit, or even the mouth of a river. This versatility makes it a crucial component in many compound words, highlighting its broad application. With only three strokes, 口 has a very simple structure, making it one of the earliest kanji learners encounter. Designated as a Grade 1 kanji, it's taught to Japanese children in their first year of elementary school. Furthermore, it's a core part of the N5 JLPT curriculum, underscoring its essential nature for beginners.

Readings

On'yomi (音読み) — Chinese-derived readings

On'yomi are readings derived from Chinese pronunciations, typically used when 口 forms part of a compound word alongside other kanji. For 口, the primary On'yomi are コウ (kō) and, less commonly, ク (ku).

The reading コウ (kō) is frequently encountered in many common and formal words. It often retains the core meaning of "mouth" or "opening," and can even refer to the number of people (as in 'mouths to feed'). For example:

人口じんこう (jinkō) — population (literally "human mouths")
口頭こうとう (kōtō) — oral, verbal (literally "mouth head")
口語こうご (kōgo) — spoken language, vernacular (literally "mouth language")

The reading ク (ku) is less common, yet it appears in specific idiomatic expressions or older compounds. A notable example is:

異口同音いくどうおん (ikudōon) — with one voice, unanimously (literally "different mouths same sound")

Kun'yomi (訓読み) — Native Japanese readings

Kun'yomi are native Japanese readings, typically used when the kanji stands alone or is followed by hiragana (okurigana) to convey its meaning directly. For 口, the main Kun'yomi are くち (kuchi) and -ぐち (-guchi).

くち (kuchi) is the most direct and common reading, referring to the anatomical mouth or, more generally, any kind of opening. For example:

口くち (kuchi) — mouth
口紅くちべに (kuchibeni) — lipstick (literally "mouth red")
口下手くちべた (kuchibeta) — poor speaker, unskillful at talking (literally "mouth unskillful")

The suffix -ぐち (-guchi) is often found in compound words, specifically denoting an entrance, exit, or a service window. This reading is particularly practical for navigating daily life in Japan. For instance:

入口いりぐち (iriguchi) — entrance (literally "entering mouth/opening")
出口でぐち (deguchi) — exit (literally "exiting mouth/opening")
窓口まどぐち (madoguchi) — service window, counter (literally "window mouth/opening")

Common Words & Compounds

The kanji 口 is incredibly versatile, forming part of many essential Japanese words. Learning these compounds will significantly expand your vocabulary.

Body Parts & Actions:
口くち (kuchi) — mouth
口笛くちぶえ (kuchibue) — whistle (made with the mouth)
口論こうろん (kōron) — argument, dispute (literally "mouth discussion")
Openings & Passageways:
入口いりぐち (iriguchi) — entrance
出口でぐち (deguchi) — exit
間口まぐち (maguchi) — frontage, width (of a shop or house opening)
河口かこう (kakō) — mouth of a river
火口かこう (kakō) — crater (mouth of a volcano)
Speech & Expression:
口頭こうとう (kōtō) — oral, verbal
口語こうご (kōgo) — spoken language
口調くちょう (kuchō) — tone of voice
口実こうじつ (kōjitsu) — pretext, excuse (literally "mouth reality")
Quantities & Figures:
人口じんこう (jinkō) — population
一口ひとくち (hitokuchi) — a bite, a mouthful; a word; a share (e.g., in a lottery ticket)
Miscellaneous Practical Terms:
窓口まどぐち (madoguchi) — service window, counter
飲み口のみくち (nomikuchi) — spout, mouthpiece, drinking quality (of sake, etc.)

Example Sentences

口くちを大おおきく開あけてください。

Kuchi o ookiku akete kudasai.

Please open your mouth wide.

この建物たてものの入口いりぐちはどこですか？

Kono tatemono no iriguchi wa doko desu ka?

Where is the entrance to this building?

出口でぐちはあちらです。

Deguchi wa achira desu.

The exit is over there.

日本にほんの人口じんこうは約やく1億おく2千万せんまん人です。

Nihon no jinkō wa yaku ichi oku ni senman-nin desu.

Japan's population is about 120 million people.

ラーメンを一口ひとくち食たべました。

Rāmen o hitokuchi tabemashita.

I took a bite of ramen.

彼かれは口くちが軽かるいので、すぐに秘密ひみつを話はなしてしまう。

Kare wa kuchi ga karui node, sugu ni himitsu o hanashite shimau.

He is a loose talker, so he immediately reveals secrets.

先生せんせいは口頭こうとうで指示しじをくれました。

Sensei wa kōtō de shiji o kuremashita.

The teacher gave me instructions orally.

この小説しょうせつは口語こうごで書かかれているので読よみやすいです。

Kono shōsetsu wa kōgo de kakarete iru node yomiyasui desu.

This novel is written in spoken language, so it's easy to read.

新あたらしい駅えきの西口にしぐちはとてもきれいです。

Atarashii eki no nishiguchi wa totemo kirei desu.

The west exit of the new station is very clean.

Related Kanji

Memory Tip

The kanji 口 (kuchi) is one of the simplest and most visually intuitive characters to learn. Its shape is a perfect square, directly resembling an open mouth or any basic opening. To remember it, simply picture a minimalistic drawing of a wide-open mouth, perhaps ready to speak, eat, or even whistle. You can also visualize it as a basic symbol for any type of portal or entryway, such as the opening of a box, a door, or a tunnel. Its clean, geometric lines make it easily distinguishable and memorable. Just think 'square opening,' and you'll easily remember 口!