underlie

verb

un·​der·​lie ˌən-dər-ˈlī 

underlay ˌən-dər-ˈlā  ; underlain ˌən-dər-ˈlān  ; underlying ˌən-dər-ˈlī-iŋ 

transitive verb

1

: to lie or be situated under

2

: to be at the basis of : form the foundation of : support

ideas underlying the revolution

3

: to exist as a claim or security superior and prior to (another)

4

archaic : to be subject or amenable to

Examples of underlie in a Sentence

A tile floor underlies the rug.

The river is underlain by limestone.

We discussed the principles that underlay their methods.

A theme of revenge underlies much of her writing.

Recent Examples on the Web

What’s kept such systems from space launch, Lai told me, is that the underlying technology wasn’t ready yet–but advances in electronics and semiconductors have changed the equation. — Alex Knapp, Forbes.com, 10 July 2026

Energy Substantiation says the structure allows the underlying oil to be treated as a spot commodity rather than a derivative, which the company says would subject it to lighter regulation. — Mia Gindis, Fortune, 9 July 2026

The resolution paradox A fundamental paradox underlies the current AI boom, though vendors seldom address it openly. — Ascend Agency, Chicago Tribune, 9 July 2026

Ryan Wideman has produced, but the underlying numbers are less flattering. — Dennis Lin, New York Times, 9 July 2026

Word History

First Known Use

before the 12th century, in the meaning defined at sense 4

Rhymes for underlie

• apply
• awry
• belie
• bely
• bigeye
• bonsai
• buckeye
• comply
• coxae
• decry
• defy
• deny

Kids Definition

underlie

verb

un·​der·​lie ˌən-dər-ˈlī 

underlay -ˈlā  ; underlain -ˈlān  ; underlying -ˈlī-iŋ 

1

: to lie or be located under

2

: to form the foundation of : support

ideas underlying the revolt