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

This kind of research is part of a broader effort in modern physics to understand how complex phenomena—such as time, consciousness, or classical reality itself—emerge from simpler underlying rules. —Prabhat Ranjan Mishra, Interesting Engineering, 25 Dec. 2025

The child had no underlying health conditions, according to county officials, and had died from the H3N1 strain Influenza A, the most common strain of the virus. —Daniel Hunt, Sacbee.com, 23 Dec. 2025

Health officials did note that the child had no underlying medical conditions. —Cecilio Padilla, CBS News, 23 Dec. 2025

Principles may underlie this decision, but so does marketing. —Spencer Kornhaber, The Atlantic, 22 Dec. 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