onsen

noun

on·​sen ˈȯn-ˌsen 

ˈän-

plural onsens or onsen

1

a

: a Japanese hot spring

When Japan began to modernize in the late 1800s, trains made it relatively easy for city dwellers to travel to the countryside, and traditional-style inns … sprang up around the onsen …

—Andrew Curry

b

: a traditionally Japanese resort or hotel with hot springs

2

: a Japanese bath in which bathers soak in a hot spring or hot-spring fed bath after first cleansing with a shower

The Japanese tradition of onsen (public baths) is high on the list of après-ski activities in Niseko [Japan].

—Jenny Hewett

also : a bathhouse or room used for such a bath

Examples of onsen in a Sentence

Recent Examples on the Web

Washing your body thoroughly before stepping into an onsen is essential. —Catherine Heald, Travel + Leisure, 22 June 2026

Sleek rooms were designed by Andre Fu, there’s a central courtyard garden that pivots around a huge cherry tree, and expansive hot spring onsen pools in the basement. —Condé Nast, Condé Nast Traveler, 2 June 2026

The Blakiston’s fish owl is the rarest owl in Japan but often visits the Yoroushi onsen in the evening. —Catherine Garcia, TheWeek, 27 May 2026

The complex includes a thermal spring garden with daybeds, two private onsen bathing pavilions, an Aqua Movement Suite for water treatments and a hydrotherapy area with a dry sauna and steam room. —Hanna Wickes, Sacbee.com, 9 May 2026

Ancient societies have long regarded the element as a form of holistic medicine for their well-being, as seen in Roman thermal baths and Japanese onsens. —Kathleen Wong, USA Today, 30 Apr. 2026

The hotel’s pièce de résistance awaits guests on the rooftop terrace: In lieu of an onsen, Soho House now has the city’s newest rooftop pool (of which there are surprisingly few in this city known for glittering views), which stays heated all winter. —Terry Ward, Robb Report, 30 Apr. 2026

Keep your hair tied up to avoid contact with the water. Phones and cameras are strictly banned to protect privacy, and swimming or splashing is prohibited; onsens are for quiet soaking. —Vivian Morelli, New York Times, 19 Nov. 2025

Indulge in the Roku Spa, with year-round access to a soothing outdoor thermal onsen (pool), fitness center, and spa treatment rooms. —Natasha Gural, Forbes.com, 26 Aug. 2025

Word History

Etymology

borrowed from Japanese, from on "warm" + sen "spring, fountain"

First Known Use

1896, in the meaning defined at sense 1