Onsen Glossary

日帰りひがえり

higaeri

Day-use visit without overnight stay. Not always available at ryokan and hotels — check in advance.

貸切 / 家族風呂かしきり / かぞくぶろ

kashikiri / kazoku-buro

Private or family bath reserved for exclusive use, for an additional fee with a time limit. Most commonly available to overnight guests and requires reservation. Less often available for day-use visitors.

混浴こんよく

konyoku

Mixed-gender bathing where men, women, and all genders can bathe together. Separate changing rooms are common but not guaranteed; towels or special bathing garments may be permitted for covering up.

湯治とうじ

tōji

Therapeutic hot spring cure — extended stays focused on healing through regular bathing. Usually used in a historical context, or for sanatorium-style facilities where patients bathe regularly over long periods to treat ailments.

湯めぐりゆめぐり

yumeguri

Hot spring hopping — visiting multiple baths in a row, often using a special pass available in onsen resort towns.

露天風呂ろてんぶろ

rotenburo

Open-air outdoor bath. One of the most iconic features of Japanese onsen, offering views of nature and seasonal scenery.

内湯うちゆ

uchiyu

Indoor bath located within the facility building, providing year-round comfort regardless of weather.

岩風呂いわぶろ

iwaburo

Stone bath, typically constructed from large natural boulders.

檜風呂ひのきぶろ

hinokiburo

Bath made of Japanese cypress (hinoki) wood, prized for its natural aroma and antibacterial properties.

水風呂みずぶろ

mizuburo

Cold water bath. Commonly used after sauna — rinse off before plunging in.

足湯あしゆ

ashiyu

Foot bath — soak your feet while remaining clothed. Often free and publicly accessible in onsen towns.

打たせ湯うたせゆ

utaseyu

Waterfall-style bath where a stream of hot water pours from above, used for shoulder and neck massage.

寝湯ねゆ

neyu

Lying-down bath — a shallow bath where bathers recline and relax in warm water.

砂湯すなゆ

sunayu

Sand bath — bathers are partially buried in naturally heated sand for therapeutic benefits. Famous in Beppu and Ibusuki.

蒸し風呂むしぶろ

mushiburo

Traditional Japanese steam bath. Bathers sit or lie in a room filled with natural hot spring steam, sometimes infused with herbs.

五右衛門風呂ごえもんぶろ

goemonburo

Small circular iron cauldron bath, usually for one person. Named after the legendary bandit Ishikawa Goemon.

野天風呂のてんぶろ

notenburo

Wild open-air bath in a natural setting with minimal man-made structures — more rustic than a typical rotenburo.

岩盤浴がんばんよく

ganbanyoku

Hot stone bathing — visitors lie on heated stone slabs. Clothing is worn, and the areas are typically mixed-gender.

掛け流しかけながし

kakenagashi

Free-flowing water directly from the source into the bath, without adding cold water, reheating, or recirculating used water. Considered the gold standard of onsen water quality.

足元湧出温泉あしもとゆうしゅつおんせん

ashimoto yūshutsu onsen

An onsen built directly over a natural spring vent — the bath sits right above the source where water rises from underground.

飲泉いんせん

insen

Drinking spring — onsen water that is safe and intended for drinking, often available at a designated tap or fountain.

湯の花ゆのはな

yu-no-hana

"Flowers of the hot spring" — mineral deposits that form on bath surfaces and mineral flakes that float in the onsen water.

加水かすい

kasui

Dilution with regular water to cool the onsen or reduce its mineral concentration.

加温かおん

kaon

Artificial heating of onsen water when the natural temperature is too low.

添加ていか

teika

Addition of chemicals to the onsen water. Most commonly refers to chlorination, even when not explicitly stated.

泉質せんしつ

senshitsu

Spring quality — the official classification system for the mineral composition of onsen water in Japan.

単純温泉たんじゅんおんせん

tanjun onsen

Simple thermal spring — the most common type in Japan. Contains relatively few dissolved minerals, but includes many famous historical hot springs.

炭酸泉 / 二酸化炭素泉たんさんせん / にさんかたんそせん

tansan-sen / nisankatanso-sen

Carbonated / carbon dioxide spring. Contains dissolved CO₂ gas that creates tiny bubbles on the skin. Rare in Japan. Scientific name: nisankatanso-sen.

塩化物泉えんかぶつせん

enkabutsu-sen

Chloride spring — one of the most common spring types in Japan. Salty taste; beneficial for muscle and joint pain, and skin conditions.

炭酸水素塩泉たんさんすいそえんせん

tansansuisoen-sen

Bicarbonate spring — often called "beauty springs" (bijin no yu) for making skin smooth. Helps dissolve sebum and gently exfoliate.

硫黄泉いおうせん

iō-sen

Sulfur spring, recognized by its distinctive egg-like smell and often milky white or yellowish water. Beneficial for skin conditions and circulation.

酸性泉さんせいせん

sansei-sen

Acidic spring with powerful sterilizing properties. Found in highland volcanic areas; can be harsh on sensitive skin.

放射能泉ほうしゃのうせん

hōshanō-sen

Radioactive (radon) spring. Contains radon at low therapeutic concentrations; traditionally used to treat gout and circulatory conditions.

含鉄泉がんてつせん

gantetsu-sen

Iron-containing spring. The water turns brown or reddish when exposed to air due to iron oxidation. Traditionally recommended for anemia.

硫酸塩泉りゅうさんえんせん

ryūsan'en-sen

Sulfate spring — promotes blood circulation. Sometimes called "wound-healing springs" (kizunoyu).

温泉街おんせんがい

onsengai

Hot spring town or district — an area where ryokan, onsen facilities, restaurants, and tourist shops have historically developed around a spring source.

脱衣所だついじょ

datsuijo

Changing room with lockers or baskets for storing clothes, located between the entrance and the bathing area.

洗い場あらいば

araiba

Washing area with seated shower stations where guests rinse and wash thoroughly before entering the bath.

番台ばんだい

bandai

Attendant's booth at the entrance of a traditional sento or onsen, where an employee monitors the premises and collects fees.

暖簾のれん

noren

Traditional fabric curtain hung at the entrance, typically color-coded (blue for men, red for women) to indicate bathing areas.

休憩所きゅうけいじょ

kyūkeijo

Rest area for relaxing after bathing, often with tatami seating, beverages, and sometimes massage chairs.

風呂桶 / 湯桶ふろおけ / ゆおけ

furooke / yuoke

Washing basin, scoop, or bucket used for rinsing at the washing station.

掛け湯かけゆ

kakeyu

A basin of clean onsen water used for pouring over yourself before entering the bath (to acclimate your body) or before leaving the bathing area (to preserve the minerals on your skin).

温泉分析書おんせんぶんせきしょ

onsen bunsekisho

Official water analysis certificate for the onsen, documenting its mineral composition, temperature, and classification. Usually displayed at the entrance to the bathing area.

洗面器せんめんき

senmenki

Small basin or bucket used for washing and rinsing the body at the washing station.

秘湯ひとう

hitō

"Secret hot springs" — a brand of the Japan Association of Secluded Hot Spring Inns (Nihon Hitō wo Mamoru Kai), which curates ryokan primarily by remoteness and difficulty of access.

湯もみゆもみ

yumomi

Traditional practice of stirring hot spring water with long wooden paddles to cool it without diluting its mineral content. Famous at Kusatsu Onsen since the Edo period.

湯守ゆもり

yumori

Hot spring guardian — the person responsible for maintaining and managing a hot spring source, ensuring proper flow and temperature.

美人の湯びじんのゆ

bijin no yu

"Beauty spring" — a marketing designation for onsen whose water is said to beautify the skin, typically bicarbonate or sulfate springs.

温泉卵おんせんたまご

onsen tamago

Eggs slow-cooked in hot spring water or steam — a popular snack in onsen towns. The white is soft and silky, while the yolk is set.

銭湯せんとう

sentō

Public bathhouse using heated tap water (as opposed to natural spring water). Traditionally serves a community hygiene role and is generally more affordable than onsen.

スーパー銭湯スーパーせんとう

sūpā sentō

Large commercial bathing complex offering a wide variety of baths, saunas, restaurants, and entertainment — a modern evolution of the traditional sento.

浴衣ゆかた

yukata

Lightweight cotton robe commonly provided at ryokan and onsen hotels, worn to and from the bath and around the facility.

地獄じごく

jigoku

Literally "hell" — geothermal areas with extreme heat, boiling water, steam vents, and sometimes toxic fumes. Famous in Beppu. Typically for viewing, not bathing.

温泉療法おんせんりょうほう

onsen ryōhō

Onsen therapy — the formal practice of using hot spring bathing for medical and therapeutic purposes, combining traditional knowledge with modern wellness approaches.