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 wrong provider skips the workup, misses underlying causes and writes prescriptions without proper follow-up bloodwork. — Samantha Agate, Charlotte Observer, 29 July 2026

Why This Is Happening Now Every category chasing this trend is answering the same underlying demand. — Olivia Shalhoup, Forbes.com, 29 July 2026

Michael Soyfer, an attorney with the Institute for Justice, the law firm that has filed lawsuits against Flock on Fourth Amendment grounds, said the underlying problem is police can use the system without a warrant or clear reason. — Eric Levenson, CNN Money, 26 July 2026

Unlike standard hearing and vision tests, these assessments examine how the brain interprets what the child hears and sees and may help identify underlying weaknesses contributing to behaviors associated with ADHD or autism. — Jillian Pretzel, Parents, 25 July 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