Meaning
坑 means pit, hole, mine shaft, or underground tunnel — any hollow dug out of the earth. This covers deliberately sunk shafts, mine galleries stretching hundreds of metres underground, and simple excavation pits. In modern Japanese the character appears almost exclusively in mining and underground-engineering vocabulary, naming the tunnels, shafts, and rock-cut passages used to extract coal, ore, and other minerals.
Two components build the character. The radical 土 (earth, soil) on the left anchors 坑 firmly in the domain of ground and rock. On the right sits 亢, which supplies the コウ pronunciation and carries a secondary sense of something strained or stretched to its limit. Together they evoke a steep excavation driving down through resistant earth — a mine shaft pressing against solid rock.
In classical Chinese, 坑 appears in some striking contexts. The most famous is 坑儒, referencing the legendary mass burial of Confucian scholars ordered by Qin Shi Huang, China's first emperor. That grim image captures the character's essence: a pit deep enough to swallow people whole. Japanese inherited the same concrete meaning, deploying 坑 in technical and historical writing about mines and underground structures.
坑 has 7 strokes and is classified under the 土 (earth) radical. It carries no primary school grade in Japan's Jōyō curriculum — its specialized, industrial nature places it firmly at JLPT N1.
Readings
On'yomi (音読み) — Chinese-derived readings
坑 has one On'yomi: コウ (kō), borrowed from Chinese, where the same character is read kēng. Every vocabulary word built on 坑 uses this reading in compound form — there is no standalone pronunciation to memorize.
Core compounds:
- 坑道 (kōdō) — mine tunnel, underground gallery
- 炭坑 (tankō) — coal mine, colliery
- 坑内 (kōnai) — inside the mine, underground interior
- 坑夫 (kōfu) — miner, mine worker
- 廃坑 (haikō) — abandoned mine, closed pit
Kun'yomi (訓読み) — Native Japanese readings
坑 has no Kun'yomi. It entered Japanese purely as a Sino-Japanese borrowing and never acquired a native pronunciation.
For a simple hole or pit, Japanese uses 穴 (ana). But 坑 and 穴 are not interchangeable. 穴 covers any kind of opening — a hole in a sock, a rabbit warren, a cave entrance. 坑 always implies something excavated and often man-made: a shaft, a gallery, a mine. Anchor the コウ reading to its mining compounds and the distinction stays clear.
Common Words & Compounds
坑 is technical vocabulary. Its compounds stay tightly grouped around mining, underground engineering, and excavation — you'll meet them in literature about Japan's coal era, museum labels, and industrial history articles.
Mining & Underground Structures:
- 坑道 (kōdō) — mine tunnel, gallery; the main passage miners travel through and along which ore is transported underground
- 炭坑 (tankō) — coal mine; the compound you'll encounter most in historical fiction and writing about Japan's industrial past
- 坑内 (kōnai) — underground, inside a mine; used in phrases such as 坑内作業 (underground work)
- 坑夫 (kōfu) — miner; a worker inside a mine shaft; also written 鉱夫 in some sources
- 坑木 (kōboku) — pit prop, mine timber; wooden supports used to prevent tunnel collapse
- 竪坑 (tatekō) — vertical shaft; descends straight into the earth for access and ore transport
- 横坑 (yokokō) — horizontal adit; a tunnel driven directly into a hillside to reach a mineral deposit
- 廃坑 (haikō) — abandoned mine; a pit no longer in operation, often discussed as post-industrial heritage
Engineering & Technical Terms:
- 坑井 (kōsei) — borehole, oil or gas well; used in petroleum and geotechnical engineering
- 坑口 (kōkō) — mine entrance, pit mouth; where an underground tunnel meets the surface
- 露天坑 (rotenkō) — open-pit mine; an excavation at the surface rather than underground
- 落とし坑 (otoshikō) — drop shaft; an internal shaft connecting different levels within a mine
Example Sentences
炭坑の歴史は地域の文化に深く根付いている。
Tankō no rekishi wa chiiki no bunka ni fukaku nezuite iru.
The history of the coal mine is deeply rooted in the local culture.
坑夫たちは毎日暗い坑道の中で働いた。
Kōfu-tachi wa mainichi kurai kōdō no naka de hataraita.
The miners worked every day inside the dark mine tunnels.
坑内の温度は夏でも低い。
Kōnai no ondo wa natsu demo hikui.
The temperature inside the mine is low even in summer.
この廃坑は今では観光地になっている。
Kono haikō wa ima de wa kankōchi ni natte iru.
This abandoned mine has now become a tourist attraction.
竪坑に降りるエレベーターが故障した。
Tatekō ni oriru erebētā ga koshō shita.
The elevator that descends into the vertical shaft broke down.
坑道の天井を支えるために坑木が使われていた。
Kōdō no tenjō wo sasaeru tame ni kōboku ga tsukawarete ita.
Pit props were used to support the ceiling of the mine tunnel.
石油会社は新しい坑井を掘削した。
Sekiyu-gaisha wa atarashii kōsei wo kussaku shita.
The oil company drilled a new borehole.
坑口の前に安全注意の看板が立っていた。
Kōkō no mae ni anzen chūi no kanban ga tatte ita.
A safety warning sign stood in front of the mine entrance.
明治時代には日本各地に炭坑が開かれた。
Meiji-jidai ni wa Nihon kakuchi ni tankō ga hirakareta.
During the Meiji era, coal mines were opened throughout Japan.
事故で坑道が崩落し、作業員が閉じ込められた。
Jiko de kōdō ga hōraku shi, sagyōin ga toji komerareta.
The mine tunnel collapsed in the accident, trapping the workers inside.
Memory Tip
Picture a pit sunk into the earth (土) so deep that anyone peering in has to crane their neck and stretch upward — that strained posture is exactly what 亢 suggests. Put them together: 土 + 亢 = 坑, a hollow that pushes the body to its limit just to look into. Tie the sound コウ (kō) to the English word "core" — miners drill toward the earth's core.
Fix the image in your mind: a narrow tunnel, headlamps in the dark, timber props groaning under rock above. 坑 is much easier to remember once you give it a real address — Hashima Island or the Miike Coal Mine both fit perfectly.