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

Those hurdles cropped up after the FDA in August approved Covid shots for those 65 and up and younger adults with at least one underlying condition that puts them at higher risk of severe illness from the virus. —Annika Kim Constantino, CNBC, 18 Sep. 2025

To help prevent infections, experts recommend drying dogs' ears after swimming or bathing, addressing underlying allergies, and performing gentle, regular ear cleanings at home. —Lucy Notarantonio, MSNBC Newsweek, 18 Sep. 2025

The vulnerability is a Type Confusion flaw in V8, Chrome’s underlying Java engine. —Zak Doffman, Forbes.com, 18 Sep. 2025

Better communication between patients and their providers about these underlying symptoms may help curb cannabis use, experts say. —Deidre McPhillips, CNN Money, 18 Sep. 2025

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