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

• abecedarian
• basal
• basic
• beginning
• elemental
• elementary
• essential
• fundamental
• introductory
• meat-and-potatoes
• rudimental
• rudimentary

Examples of underlying in a Sentence

the ocean and the underlying rock

the underlying differences between democracy and dictatorship

Recent Examples on the Web

Mass adoption requires prices that feel accessible, even if the underlying value far exceeds the cost. —Andrew Filev, Forbes.com, 14 Apr. 2025

Womanhood is the underlying theme for the debut album. —Taylor Crumpton, Essence, 14 Apr. 2025

The three levels of analysis each describe the same underlying reality—how fluids flow. —Jack Murtagh, Scientific American, 14 Apr. 2025

But the underlying metrics suggest that might not be sustainable. —Katie Woo, New York Times, 14 Apr. 2025

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