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

Another explanation is that there could be changes over time in diagnosis and reporting, or there could be other biological factors underlying why this condition appears to be increasing. — Faye Chiu, CNN Money, 21 Aug. 2026

Marex covers perpetual futures with other underlying assets globally and has begun issuing crypto perps in London. — Oliver Renick, CNBC, 21 Aug. 2026

Its discussion of the underlying study applies roughly the same figure to one kilogram of greasy wool, including carbon in wool wax, suint compounds and vegetable matter. — Alexandra Harrell, Footwear News, 21 Aug. 2026

The specific factors leading to measles epidemics vary by country, but the underlying cause everywhere is decreased vaccination rates. — Kathryn H. Jacobsen, The Conversation, 21 Aug. 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