Meaning
Steam rising off a bamboo basket of dumplings, the thick air of a Tokyo July, water vapor drifting from a hot spring — 蒸 ties all of these together. Its core meanings are steam, to steam, and the feeling of hot, humid air pressing in around you. Few kanji show up so consistently across three such different domains: the kitchen, the weather forecast, and the chemistry lab.
Structurally, 蒸 is built in three layers. At the top sits 艹 (the grass radical, くさかんむり), suggesting something growing or rising upward — just like steam climbing into the air. The middle component 丞 historically carried a sense of lifting or supporting, reinforcing that upward push. At the bottom, 灬 (fire in its four-dot form) supplies the heat. The whole character reads like a diagram: fire below, steam rising through matter above.
At 13 strokes, 蒸 is a Grade 8 (middle school) kanji that appears on the JLPT N2. You'll run into it constantly in recipes, summer weather reports, and science texts — three areas where it's hard to avoid.
Readings
On'yomi (音読み) — Chinese-derived readings
The on'yomi reading of 蒸 is ジョウ (jou), drawn from the historical Chinese pronunciation. It appears mainly in compound words (jukugo) and tends toward formal, scientific, or technical vocabulary.
- 蒸気 (jouki) — steam, vapor. One of the most common compounds, forming the basis of 水蒸気 (water vapor) and the word for steam engine.
- 蒸発 (jouhatsu) — evaporation; also used colloquially when someone has "vanished" or gone off the grid.
- 蒸留 (jouryuu) — distillation. Used in chemistry and in the production of spirits and essential oils.
- 水蒸気 (suijouki) — water vapor, steam in the scientific sense.
Kun'yomi (訓読み) — Native Japanese readings
The kun'yomi readings of 蒸 are む・す (musu), む・れる (mureru), and む・らす (murasu). These appear when the kanji stands alone or anchors native Japanese words. Cooking contexts and muggy-weather complaints are where you'll meet them most.
- 蒸す (musu) — to steam (food). The transitive action: 野菜を蒸す means "to steam vegetables."
- 蒸れる (mureru) — to become stuffy or clammy. Used for enclosed spaces that trap heat, or shoes that make your feet sweat.
- 蒸らす (murasu) — to let steam with the lid on. The step after boiling rice where you turn off the heat but keep the lid closed — crucial for fluffy results.
- 蒸し暑い (mushiatsui) — hot and humid, muggy. The go-to word for Japan's summer heat.
Common Words & Compounds
Key vocabulary using 蒸, grouped by context:
Weather & Environment
- 蒸し暑い (mushiatsui) — hot and humid, muggy
- 水蒸気 (suijouki) — water vapor
- 蒸気 (jouki) — steam, vapor
Cooking & Food
- 蒸し器 (mushiki) — steamer, steaming basket
- 蒸しパン (mushipan) — steamed bread or bun
- 蒸し焼き (mushiyaki) — braising; cooking by steaming and light grilling
- 蒸かす (fukasu) — to steam (food, especially sweet potatoes or chestnuts)
- 茶碗蒸し (chawanmushi) — savory steamed egg custard, a classic Japanese dish
Science & Industry
- 蒸発 (jouhatsu) — evaporation; disappearance
- 蒸留 (jouryuu) — distillation
- 蒸気機関 (jouki kikan) — steam engine
Everyday Expressions
- 蒸れる (mureru) — to become stuffy, to get clammy
- 蒸らす (murasu) — to let (food) steam with lid on
Example Sentences
今日は蒸し暑くて、外に出たくない。
Kyou wa mushiatsukute, soto ni detakunai.
It's so muggy today that I don't want to go outside.
野菜を蒸して食べると、栄養が逃げにくい。
Yasai wo mushite taberu to, eiyou ga nige nikui.
Steaming vegetables keeps more nutrients in than boiling.
鍋に蓋をして、五分ほど蒸らしてください。
Nabe ni futa wo shite, gofun hodo murashite kudasai.
Put a lid on the pot and let it steam for about five minutes.
水が蒸発すると、水蒸気になる。
Mizu ga jouhatsu suru to, suijouki ni naru.
When water evaporates, it turns into water vapor.
蒸留水は純粋な水で、実験によく使われる。
Jouryuusui wa junsui na mizu de, jikken ni yoku tsukawareru.
Distilled water is pure water and is often used in experiments.
梅雨の季節は蒸し暑い日が続く。
Tsuyu no kisetsu wa mushiatsui hi ga tsuzuku.
The rainy season brings one muggy day after another.
茶碗蒸しは、日本の伝統的な料理だ。
Chawanmushi wa, nihon no dentouteki na ryouri da.
Chawanmushi is a traditional Japanese dish — silky steamed egg custard served in a small cup.
この靴は通気性が悪くて、足が蒸れやすい。
Kono kutsu wa tsuukisei ga warukute, ashi ga mure yasui.
These shoes have poor ventilation, so my feet tend to get sweaty and stuffy.
蒸気機関車は明治時代に日本に導入された。
Jouki kikansha wa Meiji jidai ni Nihon ni dounyuu sareta.
Steam locomotives were introduced to Japan during the Meiji era.
彼は突然蒸発してしまい、誰も行方を知らない。
Kare wa totsuzen jouhatsu shite shimai, dare mo yukue wo shiranai.
He suddenly vanished without a trace, and nobody knows his whereabouts.
Memory Tip
To remember 蒸, picture a bamboo steamer basket sitting over a wok. Look at the kanji itself: the 草冠 (艹) at the top represents the steam or green vegetables rising upward, the middle section 丞 is like the steamer basket holding everything in place, and the four dots at the bottom 灬 are the flames of the fire underneath. Fire (灬) heats water, steam rises through the basket (丞), and floats upward like grass (艹) growing toward the sky. Every time you feel the sticky summer heat in Japan and hear someone say むし暑い, remember this layered image: fire below, steam rising above.