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

Last month, Texas announced the outbreak’s first death, a school-age child who was not vaccinated and had no underlying conditions. —Neha Mukherjee, CNN, 21 Mar. 2025

This multi-faceted approach addresses both immediate needs and underlying causes of homelessness. —Courier-News, Chicago Tribune, 20 Mar. 2025

Not officially, of course: in keeping with the underlying mission of the IOC, Bach would never do something as openly partisan as endorsing a successor. —Blythe Lawrence, Forbes, 19 Mar. 2025

Scientists from the University of Warsaw have gleaned insights into the underlying physics of channeling that will help coffee lovers achieve more consistent results when brewing espresso. —Ars Technica, 17 Mar. 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