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

But Saunders noted that Amazon is not immune to outside factors, as global markets tighten and underlying costs climb. —Michelle Chapman, Fortune, 28 Oct. 2025

These symptoms, known as urinary urgency and frequency, have many causes, including infections and underlying health conditions. —Lindsay Curtis, Health, 25 Oct. 2025

The wafer-thin coating of clay remained long after the underlying tissues decayed completely, retaining their detailed morphology and forming a perfect clay mask. —Amanda Schupak, CNN Money, 23 Oct. 2025

Of course, struggling with focus can be a sign of an underlying health condition, like attention deficit hyperactivity disorder (ADHD). —Korin Miller, SELF, 23 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