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

• 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

The underlying rationale behind the shift is the argument that centralized federal systems create moral hazards, stifle local innovation, and make states overly reliant on Washington. —Alexander Puutio, Forbes.com, 8 July 2025

His fastball run value ranks in the 90th percentile, and his underlying numbers align closely with his actual results. —Cody Stavenhagen, New York Times, 8 July 2025

Secondary hyperhidrosis is caused by an underlying issue like medications, infections, endocrine disorders, or even certain cancers. —Lauryn Higgins, Time, 7 July 2025

The underlying idea is that there’s a divide between the establishment Democrats and populist-minded progressive Democratic candidates. —Christian Paz, Vox, 6 July 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