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

After the therapist interacts with the AI persona, the AI is to ultimately divulge, when asked by the therapist, what the underlying factors were. —Lance Eliot, Forbes.com, 27 Jan. 2026

The underlying lawsuit, filed in December, alleges that federal officers violated the First and Fourth Amendment rights of six protesters. —Kaelan Deese, The Washington Examiner, 27 Jan. 2026

For his part, Falkowski has turned to the theoretical study of scattering amplitudes, a growing research area focused on the geometric patterns underlying particle interaction statistics, patterns that could point toward a truer perspective on the quantum world. —Quanta Magazine, 26 Jan. 2026

The investigation’s underlying premise has been widely rejected by legal experts and medical professionals, according to Racela. —City News Service, Daily News, 26 Jan. 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