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

Additional amenities are extensive, with a subterranean garage, safe rooms, three elevators, and a full suite of back-of-house spaces, including laundry rooms, art storage, and even an X-ray room. —Wendy Bowman, Robb Report, 29 Apr. 2026

Snorkel in subterranean rivers, swim with dolphins (for an extra fee, with reservations), duck at the sound of macaws screeching overhead, wander through a Day of the Dead display, and swing in a hammock beside a turquoise cove. —Condé Nast, Condé Nast Traveler, 29 Apr. 2026

Formosan termites are subterranean termites that form large, highly destructive colonies in the South. —Karen Brewer Grossman, Southern Living, 27 Apr. 2026

Guests went diving under tables as the scene unfolded and some reported hearing shots outside the vast subterranean ballroom in the Washington Hilton where the event was being held. —Collin Binkley, Chicago Tribune, 26 Apr. 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