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

The idea is to broaden the base of potential investors in the underlying crypto holding. —Matt Peterson, CNBC, 9 June 2026

Siri’s underlying reasoning rests on a new generation of Apple Foundation Models, including a top-tier cloud model that the company calls AFM 3 Cloud Pro, which is custom-built for Apple hardware. —Eric Sullivan, Scientific American, 9 June 2026

Large randomized trials testing specific food protocols don’t yet exist, but the hormonal physiology underlying the general framework is well documented. —Allison Palmer, Fort Worth Star-Telegram, 8 June 2026

But in making their arguments, the authors went further, addressing fundamental questions of politics by laying out the political theory that underlies that Constitution. —Jordan Cash, The Conversation, 8 June 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