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 sample was just six young men, so results may vary, but the underlying biology is well-established. —Allison Palmer, Miami Herald, 12 May 2026

But Hadler does not believe that fibromyalgia should be classified as a disease in the traditional biomedical sense, because medicine has yet to identify a discrete, demonstrable pathophysiological process underlying it. —Jason Liebowitz, The Atlantic, 12 May 2026

Phone apps and not phone apps Google seems to be avoiding an explicit mention of Android when discussing Googlebooks, but that’s the underlying software. —ArsTechnica, 12 May 2026

The ages of the passengers range from late 20s to early 80s, with older people and those with underlying health conditions at higher risk of severe outcomes. —Lex Harvey, CNN Money, 12 May 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