Meaning
肝 has two tightly linked meanings. On the literal side, it refers to the liver. Japanese tradition long viewed the liver as the seat of courage and spirit, so the kanji extended naturally to mean guts, nerve, and anything essential or crucial. These two sides feed distinct vocabulary clusters: medical and formal contexts use the KAN reading, while expressions about boldness and urgency tend to draw on きも.
肝 breaks into two components. On the left is 月, the flesh radical — derived from 肉 (meat), not from the moon character, though they look identical. This same radical marks body-part kanji like 腸 (intestines), 脳 (brain), and 肺 (lungs). On the right, 干 (KAN) acts as a phonetic indicator, providing the on'yomi reading of カン.
Seven strokes make 肝 fairly compact, but as a secondary-school Joyo kanji, it rarely appears in elementary reading material. Open a novel, a newspaper, or a formal document and it surfaces quickly — usually in one of three roles: a medical context (the liver), a formal modifier (vital, essential), or an idiom about fear or courage.
At JLPT N1, 肝 is hard to avoid. High-frequency items like 肝心 (essential, crucial), 肝臓 (liver), and 度肝を抜く (to astonish) all depend on it. So do the everyday idioms 肝を冷やす and 肝っ玉 — phrases that come up regularly in casual Japanese conversation.
Readings
On'yomi (音読み) — Chinese-derived readings
The on'yomi is カン (KAN), tracing back to the ancient Chinese pronunciation. In compound words (jukugo), KAN is the default — when 肝 appears next to another kanji, assume KAN. It dominates formal, written, and medical Japanese.
- 肝臓 (kanzō) — liver (the organ); the standard medical and everyday term for the liver, appearing constantly in health articles and medical documents
- 肝心 (kanjin) — essential, crucial, most important; literally combines "liver" (肝) and "heart" (心), the two organs deemed most vital to life
- 肝要 (kanyō) — vital, of utmost importance; a more formal or literary synonym of 肝心, often found in essays and speeches
- 肝炎 (kanen) — hepatitis; inflammation of the liver; a common topic in health and medical Japanese
- 肝油 (kanyu) — cod liver oil; a dietary supplement known for its vitamins
- 肝硬変 (kankōhen) — liver cirrhosis; a serious chronic liver disease frequently mentioned in medical contexts
Kun'yomi (訓読み) — Native Japanese readings
The kun'yomi is きも (kimo), the reading used when 肝 stands alone or forms colloquial compounds. At a yakitori restaurant, きも means chicken liver — physical and direct. In conversation, the same word describes guts or nerve. It feels rawer and more personal than the clinical KAN compounds.
- 肝 (kimo) — liver (as food, e.g., at a yakitori restaurant); guts, nerve, courage in a figurative sense
- 肝っ玉 (kimottama) — guts, nerve, bold spirit; the phrase 肝っ玉母さん (kimottama okāsan) describes a tough, courageous mother
- 肝試し (kimodameshi) — a test of courage; the classic Japanese summer activity of walking through a dark, supposedly haunted place
- 度肝 (dokimo) — used in the iconic phrase 度肝を抜く (dokimo wo nuku), meaning to utterly astonish or blow someone away
Common Words & Compounds
The main 肝 vocabulary breaks into four groups. Knowing which group a word belongs to helps predict both the reading and the register.
Medical & Body-related:
- 肝臓 (kanzō) — liver (organ); the standard term, appears on health checkup results and medical documents
- 肝炎 (kanen) — hepatitis; commonly discussed in public health campaigns in Japan
- 肝硬変 (kankōhen) — liver cirrhosis; a serious condition caused by long-term liver damage
- 肝臓がん (kanzōgan) — liver cancer; appears in cancer awareness materials
- 肝油 (kanyu) — cod liver oil; old-fashioned but still recognized health supplement
Essential & Important:
- 肝心 (kanjin) — essential, crucial; one of the most useful N1 vocabulary items using this kanji
- 肝要 (kanyō) — vital, of the utmost importance; appears in formal writing and speeches
- 肝心要 (kanjin kaname) — the absolute most critical point; an emphatic combination used for strong emphasis
Courage & Personality (using きも):
- 肝っ玉 (kimottama) — guts, boldness, steely nerve; describes someone with exceptional courage
- 肝試し (kimodameshi) — test of courage; a beloved summer tradition at Japanese festivals and schools
- 度肝 (dokimo) — extreme guts; used exclusively in the phrase 度肝を抜く (to astonish, to blow away)
Common Idioms & Expressions:
- 肝に銘じる (kimo ni meijiru) — to take to heart, to keep firmly in mind; you will hear this in graduation speeches and formal advice
- 肝を冷やす (kimo wo hiyasu) — to be scared stiff, to have your heart skip a beat; literally "to cool the liver"
- 肝を潰す (kimo wo tsubusu) — to be startled or frightened; literally "to crush the liver"
- 肝胆 (kandan) — liver and gallbladder; used in the set phrase 肝胆相照らす (kandan ai terasu), meaning to be bosom friends who understand each other completely
Example Sentences
この計画で肝心なのは、予算をしっかり守ることです。
Kono keikaku de kanjin na no wa, yosan wo shikkari mamoru koto desu.
The most crucial thing in this plan is to strictly stick to the budget.
医者は彼の肝臓に問題があると言いました。
Isha wa kare no kanzō ni mondai ga aru to iimashita.
The doctor said there was a problem with his liver.
あの事故のニュースを聞いて、肝を冷やしました。
Ano jiko no nyūsu wo kiite, kimo wo hiyashimashita.
Hearing the news about that accident scared me stiff.
この言葉を肝に銘じて、毎日努力してください。
Kono kotoba wo kimo ni meijite, mainichi doryoku shite kudasai.
Take these words to heart and make an effort every single day.
あの女優は肝っ玉が据わっていて、どんな役でもこなせる。
Ano joyū wa kimottama ga suwatte ite, donna yaku demo konaseru.
That actress has nerves of steel and can handle any role.
子供たちは夏に肝試しをするのが大好きだ。
Kodomotachi wa natsu ni kimodameshi wo suru no ga daisuki da.
The children love doing courage tests in the summer.
マジシャンの手品は観客の度肝を抜いた。
Majishan no tejina wa kankyaku no dokimo wo nuita.
The magician's trick completely blew the audience away.
健康のために肝臓に負担をかけないよう、お酒は控えています。
Kenkō no tame ni kanzō ni futan wo kakenai yō, osake wa hikaete imasu.
For my health, I'm cutting back on alcohol so as not to burden my liver.
肝心なことを忘れて、会議に資料を持ってくるのをうっかりしてしまった。
Kanjin na koto wo wasurete, kaigi ni shiryō wo motte kuru no wo ukkari shite shimatta.
I forgot the most important thing — I carelessly left the documents for the meeting behind.
彼は肝炎と診断されて、しばらく入院することになった。
Kare wa kanen to shindan sarete, shibaraku nyūin suru koto ni natta.
He was diagnosed with hepatitis and ended up being hospitalized for a while.
Memory Tip
Two elements, two hooks. On the left is 月 — not the moon here, but flesh (this radical comes from 肉). On the right is 干, meaning dry. Picture the liver: the organ that works around the clock without rest, silently filtering everything. That relentless endurance is exactly what 肝っ玉 describes in a person.
A second angle: 肝心 literally pairs liver (肝) with heart (心) — your two most non-negotiable organs. When something is 肝心, it's as critical as both at once. And for 度肝を抜く, picture someone so shocked that their liver gets yanked out. That visceral image captures why the phrase means "to completely astonish."
Flesh (月) + dry (干) = the tireless organ, and the word for the nerve to match it.