underpinning

American  

[uhn-der-pin-ing] / ˈʌn dərˌpɪn ɪŋ /

noun

1. a system of supports beneath a wall or the like.

2. Often underpinnings. a foundation or basis.

   to uncover the emotional underpinnings of an illness.

3. Informal. underpinnings,

   1. underwear, especially women's underwear.

   2. the legs.

---

underpinning British  

/ ˈʌndəˌpɪnɪŋ /

noun

1. a structure of masonry, concrete, etc, placed beneath a wall to provide support

---

Etymology

Origin of underpinning

First recorded in 1480–90; under + pin + -ing ¹

Example Sentences

Here is a look at some of the key elements of the vehicles underpinning the flight.

From The Wall Street Journal • Apr. 1, 2026

And an underpinning of loneliness and suppressed yearning.

From Los Angeles Times • Mar. 18, 2026

"But those are just simulations, not the real universe. Now we have a foundation which can let us know if some of the astrophysics underpinning those simulations is correct."

From Science Daily • Mar. 8, 2026

Supreme Court decision that annulled the tariffs underpinning that agreement.

From Barron's • Mar. 7, 2026

For more than eighteen months, from mid-2005 until early 2007, there had been this growing disconnect between the price of subprime mortgage bonds and the value of the loans underpinning them.

From "The Big Short" by Michael Lewis