underpinning

noun

un·​der·​pin·​ning ˈən-dər-ˌpi-niŋ 

1

: the material and construction (such as a foundation) used for support of a structure

2

: something that serves as a foundation : basis, support

—often used in plural

the philosophical underpinnings of educational methods

3

: underwear

—usually used in plural

4

: a person's legs

—usually used in plural

Synonyms

• basis
• foundation
• bedrock
• cornerstone

Examples of underpinning in a Sentence

the underpinnings of the theory have recently been called into question

the underpinnings of the bridge were seriously damaged in the collision

Recent Examples on the Web

Such is the case with a machine all but forgotten through time, though pivotal in forging the early underpinnings of a now-fabled automaker’s legacy. —Viju Mathew, Robb Report, 9 June 2025

Taken together, these developments suggest that market participants are placing greater emphasis on companies that provide the technical underpinnings of broader digital ecosystems. —Arthur Mouratov, Forbes.com, 2 June 2025

With sufficient legal underpinning—including reciprocal access agreements among the three Asian allies— each of these arrangements could be expanded to include forces from the other members. —Ely Ratner, Foreign Affairs, 27 May 2025

This philosophical underpinning drives the company beyond mere resurrection spectacles — a critique often levied by academic skeptics following the company’s milestone de-extinction announcement. —Nia Bowers, USA Today, 24 May 2025

Word History

First Known Use

15th century, in the meaning defined at sense 1

Rhymes for underpinning

• beginning
• binning
• dinning
• ginning
• grinning
• inning
• pinning
• sinning
• skinning
• spinning
• thinning
• tinning

Kids Definition

underpinning

noun

un·​der·​pin·​ning ˈən-dər-ˌpin-iŋ 

1

: the foundation used for support of a structure

2

: prop entry 1, support

3

: a person's legs

—usually used in plural