basement

American  

[beys-muhnt] / ˈbeɪs mənt /

noun

1. a story of a building, partly or wholly underground.

2. (in classical and Renaissance architecture) the portion of a building beneath the principal story, treated as a single compositional unit.

3. the lowermost portion of a structure.

4. the substructure of a columnar or arched construction.

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basement British  

/ ˈbeɪsmənt /

noun

1. 1. a partly or wholly underground storey of a building, esp the one immediately below the main floor Compare cellar

   2. ( as modifier )

      a basement flat

2. the foundation or substructure of a wall or building

3. geology a part of the earth's crust formed of hard igneous or metamorphic rock that lies beneath the cover of soft sedimentary rock, sediment, and soil

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Etymology

Origin of basement

First recorded in 1720–30; base ¹ + -ment

Explanation

A basement is a room that's below ground level, underneath the first floor. You might have a laundry room with a washer and dryer in your basement. Some basements are partially under the level of the street, while others are completely below ground. Many, though not all, houses and larger buildings have basements. Some basements are "finished," with carpeting and solid ceilings and walls, but more often they're very basic rooms used for storage. The word dates from 1730, most likely from the Italian basamento, "column base."

Example Sentences

While tinkering in his basement laboratory, he used it regularly to communicate with his invalid wife, who was confined to her bedroom upstairs.

From The Wall Street Journal • Apr. 12, 2026

Prosecutors believe the fire started when champagne bottles with sparklers attached were raised too close to the ceiling in the bar's basement level, igniting the sound insulation foam.

From Barron's • Apr. 8, 2026

Streets as well as the basement of the local police station in Nea Makri were flooded.

From BBC • Apr. 2, 2026

The second, in the basement of the house Manetta shares with her mother, drew 10.

From Salon • Mar. 28, 2026

I think about Dad in the basement, struggling to find a new job.

From "South of Somewhere" by Kalena Miller

Related Words

• cellar
• storage
• vault