underpin

American  

[uhn-der-pin] / ˌʌn dərˈpɪn /

verb (used with object)

underpinned, underpinning

1. to prop up or support from below; strengthen, as by reinforcing a foundation.

2. to replace or strengthen the foundation of (a building or the like).

3. to furnish a foundation for; corroborate.

   The author's conclusions are underpinned by references to experimental findings.

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underpin British  

/ ˌʌndəˈpɪn /

verb

1. to support from beneath, esp by a prop, while avoiding damaging or weakening the superstructure

   to underpin a wall

2. to give corroboration, strength, or support to

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Etymology

Origin of underpin

First recorded in 1515–25; under- + pin

Explanation

To underpin is to justify or support the ideas behind something, the way your extensive research underpins your self-published book on ice cream trucks in the United States. Whenever you substantiate someone's claims, theories, or stories, you underpin them. A slightly different way to underpin is to form the basis or foundation of something: "A philosophy of empathy and kindness underpins all the interactions at my wonderful summer camp." This verb can also be used in a more literal way, to mean "support from below," the way the foundation of a house underpins everything that's built on top of it.

Example Sentences

Much of that classification still rests on 2011 data, even though many areas have since transformed, blurring the lines that underpin policy.

From BBC • Mar. 31, 2026

These concerns underpin the Scottish government's long-standing opposition to retaining BST during winter.

From BBC • Mar. 27, 2026

Arm’s ambitious revenue targets, partly driven by its newfangled chip business, also underpin the stock upgrade.

From Barron's • Mar. 26, 2026

It also requires the U.S. and its allies to maintain a decisive lead in emerging technologies, such as semiconductors and artificial intelligence, that underpin modern power.

From The Wall Street Journal • Mar. 24, 2026

The AIG FP traders present were shocked by how little thought or analysis seemed to underpin the subprime mortgage machine: It was simply a bet that home prices would never fall.

From "The Big Short" by Michael Lewis