Meaning
The kanji 骨 means bone or skeleton — but it reaches well beyond anatomy. Japanese speakers use it to describe the structural frame of a building, the core of a plan, and the sheer effort required to do difficult work. This range from the physical to the abstract is what makes 骨 worth knowing well.
骨 is a pictograph built from two parts. The upper section, 冎, represents a joint — two bones meeting at a hinge, an early visual shorthand for skeletal anatomy. The lower part, 月, here acts not as "moon" but as the flesh/body radical (abbreviated from 肉), which appears across many body-related kanji. Set together, the two elements show bones embedded in flesh — the hard inner structure that gives a living body its shape.
骨 has 10 strokes and appears in the grade 6 curriculum — relatively late in elementary school, fitting for a kanji with this much conceptual range. It heads its own radical group (骨部), and other kanji sharing this radical tend to involve bones or skeletal anatomy.
Figuratively, 骨 carries ideas of backbone, resilience, and grit. A 骨のある人 is someone with real substance and determination — the kind of person who doesn't bend easily. The expression 骨が折れる literally means "a bone breaks," but idiomatically it just means something is hard or takes serious effort. No injury involved.
Readings
On'yomi (音読み) — Chinese-derived readings
The on'yomi is コツ (kotsu). It shows up mainly in compound words and medical vocabulary — the sort of reading you'll encounter in a clinic or textbook. When 骨 pairs with another kanji, コツ is almost always the reading.
- 骨格 (kokkaku) — skeleton, bone structure, physique; also used figuratively for the framework or outline of an argument
- 骨折 (kossetsu) — bone fracture; a standard medical term
- 骨髄 (kotsuzui) — bone marrow; used figuratively in 骨髄に染みる ("to feel it in one's bones")
- 骨盤 (kotsuban) — pelvis
- 軟骨 (nankotsu) — cartilage; 軟 means "soft," making the contrast with hard bone explicit
- 鎖骨 (sakotsu) — collarbone, clavicle
Kun'yomi (訓読み) — Native Japanese readings
The kun'yomi is ほね (hone). This is what you'll hear in everyday conversation — someone picking a fish bone from their meal, or grumbling that a task is 骨が折れる. It covers both the literal and the figurative.
- 骨 (hone) — bone (standalone)
- 背骨 (sebone) — spine, backbone; 背 means "back"
- 骨組み (honegumi) — framework, structural outline; used for buildings, stories, plans
- 骨折り (honeori) — hard work, great effort; literally "breaking bones"
- 骨身 (honemi) — body and soul; used in expressions of working with every part of oneself
Common Words & Compounds
骨 turns up across a range of compound words — from clinic vocabulary to everyday idioms. Here are the key ones, grouped by theme:
Anatomy & Medicine
- 骨格 (kokkaku) — skeleton, bone structure
- 骨折 (kossetsu) — bone fracture
- 骨髄 (kotsuzui) — bone marrow
- 骨盤 (kotsuban) — pelvis
- 軟骨 (nankotsu) — cartilage
- 鎖骨 (sakotsu) — collarbone
- 肋骨 (rokkotsu) — rib
Structure & Framework
- 骨組み (honegumi) — framework, structural outline
- 背骨 (sebone) — spine, backbone
- 骨子 (kosshi) — gist, main points, core outline of a document or plan
Effort & Character
- 骨折り (honeori) — hard work, pains taken
- 骨身 (honemi) — body and soul, one's entire being
- 骨のある (hone no aru) — having backbone, showing grit
- 骨が折れる (hone ga oreru) — to be difficult, to take great effort (idiomatic)
Other Common Uses
- 骨董 (kottou) — antique, curio
- 骨頂 (kocchō) — the height of, the epitome of (often negative: 愚の骨頂 = the height of stupidity)
Example Sentences
犬が骨をかじっている。
Inu ga hone wo kajitte iru.
The dog is gnawing on a bone.
転んで腕の骨を折ってしまった。
Koronde ude no hone wo otte shimatta.
I fell and broke a bone in my arm.
この仕事は骨が折れる。
Kono shigoto wa hone ga oreru.
This job takes a lot of effort.
彼は骨のある人間だと思う。
Kare wa hone no aru ningen da to omou.
I think he's a person with real backbone.
医者はレントゲンで骨折を確認した。
Isha wa rentogen de kossetsu wo kakunin shita.
The doctor confirmed the fracture on the X-ray.
この建物の骨組みは鉄でできている。
Kono tatemono no honegumi wa tetsu de dekite iru.
This building's framework is made of iron.
彼女は骨身を惜しまず働いた。
Kanojo wa honemi wo oshimazu hataraita.
She worked body and soul, holding nothing back.
骨髄バンクに登録する人が増えている。
Kotsuzui banku ni touroku suru hito ga fuete iru.
More people are signing up with the bone marrow bank.
その計画の骨子を説明してください。
Sono keikaku no kosshi wo setsumei shite kudasai.
Please explain the core points of the plan.
これほど人を裏切るとは、愚の骨頂だ。
Kore hodo hito wo uragiru to wa, gu no kocchō da.
Betraying someone like this — it's the height of foolishness.
Memory Tip
The top half of 骨 (冎) looks like a joint — two bones at a hinge, a miniature knee or elbow. The bottom half (月) is the flesh that wraps around them. Read the whole character as: bones inside a body.
For the readings: ほね (hone) rhymes loosely with "bone" itself — close enough to stick. For コツ (kotsu), imagine two bones knocking together with a short, hard clunk. Brief and blunt, just like the syllable.