underlying

1 of 2

adjective

un·​der·​ly·​ing ˌən-dər-ˈlī-iŋ 

1

a

: lying beneath or below

the underlying rock is shale

b

: basic, fundamental

an investigation of the underlying issues

2

: evident only on close inspection : implicit

3

: anterior and prior in claim

underlying mortgage

4

: of or being present in deep structure

underlying word order

underlying

2 of 2

present participle of underlie

Synonyms of underlying

Adjective

• basic
• rudimentary
• elementary
• fundamental
• introductory

Examples of underlying in a Sentence

Adjective

the ocean and the underlying rock

the underlying differences between democracy and dictatorship

Recent Examples on the Web

Adjective

Chomsky’s influential criticism of behaviorist explanations of language helped turn scientific attention toward the mental processes underlying language acquisition and use. — Encyclopedia Britannica, 8 Sep. 2026

Meanwhile, there are rising concerns about the potential cybersecurity risks posed by AI agents and their underlying foundation models, and the country faces a growing backlash against AI data centers and the companies that are building them. — Jonathan Vanian, CNBC, 8 Sep. 2026

However, geographic shifts alone do not necessarily remove underlying supply chain risks. — Sj Studio, Footwear News, 8 Sep. 2026

The company’s addition of another high-capacity facility in Louisiana is emblematic of the new NSTP’s lofty goals, as well as its underlying purpose, says Jonathan McDowell, an astrophysicist who tracks launch and spaceport statistics. — Elizabeth Howell, Scientific American, 7 Sep. 2026

Word History

First Known Use

Adjective

1611, in the meaning defined at sense 1a

Rhymes for underlying

• applying
• belying
• complying
• decrying
• defying
• denying
• implying
• outlying
• relying
• replying
• supplying
• undying

Kids Definition

underlying

adjective

un·​der·​ly·​ing ˌən-dər-ˌlī-iŋ 

1

: lying under or below

the underlying rock

2

: fundamental entry 1 sense 1

Medical Definition

underlying

adjective

un·​der·​ly·​ing -ˌlī-iŋ 

: serving as a basis or cause (as of secondary symptoms)

the underlying brain malformation that caused the hydrocephalus

—R. M. Henig