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

More than half of the companies surveyed cited security as the primary underlying reason for providing personal use of corporate jet and chauffeur services. —Amanda Gerut, Fortune, 21 Oct. 2025

The mother-in-law even offered to pay for the woman’s share of the bachelorette weekend, but that didn't solve the underlying issues. —Ashley Vega, PEOPLE, 20 Oct. 2025

However, all of them follow the same underlying themes of good triumphing over evil and light over darkness. —Saman Shafiq, USA Today, 19 Oct. 2025

Having innate gifts doesn't always translate into understanding the underlying mechanics behind them, not to mention being able to communicate that understanding in a digestible way. —Shaun McAvoy, MSNBC Newsweek, 17 Oct. 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