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

The electrical response could therefore be switched without substantially changing the material’s underlying magnetic interactions. — Neetika Walter, Interesting Engineering, 12 Aug. 2026

The Fed is concerned about the underlying inflationary pressures, not every idiosyncratic change in the price level. — Bill Conerly, Forbes.com, 12 Aug. 2026

Saft was equally unsparing about the underlying assessment math, which values co-ops and condominiums differently than houses. — Catherina Gioino, Fortune, 11 Aug. 2026

Those most at risk of infection include patients with severe underlying medical conditions. — Melissa Rudy, FOXNews.com, 11 Aug. 2026

Word History

First Known Use

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