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 of subterranean

• underground

Examples of subterranean in a Sentence

a subterranean bunker that supposedly could withstand even an atomic blast

Recent Examples on the Web

After reviewing over 30 years of monitoring data, entomologists at the University of Florida (UF) now say both the Formosan and Asian subterranean termites (Coptotermes formosanus and Coptotermes gestroi) are expanding their range of destruction. —Andrew Paul, Popular Science, 5 Feb. 2026

For most of us, our home are our biggest investment, and subterranean termites may require a multi-pronged treatment approach. —Arricca Elin Sansone, Southern Living, 4 Feb. 2026

Or, head downstairs in their wine-cellar-style dining space a late night subterranean drink. —Jessica Chapel, Condé Nast Traveler, 30 Jan. 2026

The subterranean lounge is built on the garden level of a brick townhouse perched atop the hills of Mount Adams, Cincinnati's most beautiful neighborhood. —Keith Pandolfi, Cincinnati Enquirer, 30 Jan. 2026

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