underlying

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

Synonyms of underlying

• basic
• rudimentary
• elementary
• fundamental
• introductory

Examples of underlying in a Sentence

the ocean and the underlying rock

the underlying differences between democracy and dictatorship

Recent Examples on the Web

For Manuel, the moral universe of the golf course — as well as the game itself — functions as an underlying metaphor for the Philippines’ cycles of political stasis. —Patrick Brzeski, HollywoodReporter, 14 Feb. 2026

Healthcare costs remain an ongoing topic across organizations, even as the underlying mechanics of how they are calculated and distributed can be complex. —Lyssanoel Frater, USA Today, 13 Feb. 2026

In these circumstances, the centers work mainly to stabilize acute withdrawal symptoms rather than to home in on underlying factors that may drive substance use and possible return to use. —Emma Fenske, The Conversation, 12 Feb. 2026

The ETFs use option contracts to shield investors from a set percentage of losses on an underlying index, typically the S & P 500 . —Michelle Fox, CNBC, 11 Feb. 2026

Word History

First Known Use

1611, in the meaning defined at sense 1a

Rhymes for underlying

• amplifying
• beautifying
• certifying
• clarifying
• classifying
• codifying
• crucifying
• edifying
• falsifying
• fortifying
• glorifying
• gratifying

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