subterranean

adjective

sub·​ter·​ra·​nean ˌsəb-tə-ˈrā-nē-ən 

-nyən

variants or less commonly subterraneous

ˌsəb-tə-ˈrā-nē-əs 

-nyəs

1

: being, lying, or operating under the surface of the earth

2

: existing or working in secret : hidden

a subterranean network of criminals

subterraneanly adverb

or less commonly subterraneously

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Go Underground With Subterranean

A tunnel is a subterranean road or pathway, and a subway is a subterranean railway. The subterranean vaults at Fort Knox hold billions of dollars of gold reserves. Subterranean reservoirs called aquifers are tapped for water; in places where the pressure on the subterranean water is great enough, a hole drilled in the ground will bring it bubbling to the surface.

Synonyms

• underground

Examples of subterranean in a Sentence

a subterranean bunker that supposedly could withstand even an atomic blast

Recent Examples on the Web

Both men spent a lot of time in their respective bunkers during World War II, and those subterranean headquarters spoke volumes about their respective leadership styles. —Bryce Hoffman, Forbes.com, 3 Aug. 2025

While Longfellow Bar made last year’s list, this year Ghost Baby, the subterranean bar in Over-the-Rhine, won the honors. —Keith Pandolfi, Cincinnati Enquirer, 31 July 2025

Welcome to Ghost Baby, Cincinnati’s very subterranean cocktail bar. —USA Today, 30 July 2025

The Alamo's Facebook page confirms it: the bike famously chased by Pee-wee Herman (the late Paul Reubens) in San Antonio after a shady medium pointed him to the mission's non-existent subterranean levels is becoming a permanent part of the tourist attraction. —Ana Gutierrez, Austin American Statesman, 18 July 2025

Word History

Etymology

Latin subterraneus, from sub- + terra earth — more at thirst

First Known Use

1603, in the meaning defined at sense 1

Rhymes for subterranean

• romanian
• roumanian
• rumanian
• ukrainian
• cenomanian
• lithuanian
• pennsylvanian
• pomeranian
• mediterranean

Kids Definition

subterranean

adjective

sub·​ter·​ra·​nean ˌsəb-tə-ˈrā-nē-ən 

-nyən

1

: being, lying, or operating under the surface of the earth

2

: existing or working in secret : hidden