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

More so because leading organizations — both traditional and crypto-native — are building practical, hands-on solutions to this end, now that the underlying frameworks are mostly ready and in place. —Lawrence Wintermeyer, Forbes.com, 11 Sep. 2025

Protein aggregation underlies devastating disorders such as Alzheimer’s plaques, Parkinson’s Lewy bodies, and misfolded proteins in cancer. —Aamir Khollam, Interesting Engineering, 11 Sep. 2025

Novavax was approved for those 12 and older with an underlying condition and people over 65. —Hannah Pinski, The Courier-Journal, 11 Sep. 2025

The Fed, though, is more focused on services costs as signals of underlying inflation. —Jeff Cox, CNBC, 11 Sep. 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