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

Elevators in each wing allow guests to discreetly scoot to the subterranean spa in their Turkish linen bathrobes. — Condé Nast, Condé Nast Traveler, 6 Nov. 2026

Other highlights include an office with its own entrance, an exercise room, a cozy den, and a subterranean multi-car garage notched into the hillside. — Wendy Bowman, Robb Report, 6 Nov. 2026

The subterranean space was as ample as Dolly’s most famous asset—a surprising rarity in downtown Manhattan. — Simone Cook, Vogue, 1 Nov. 2026

The first subterranean fish known to live in the Ganges basin was discovered after zoologists spotted it on TikTok and pumped it out of a borehole. — J. B. MacKinnon, Harpers Magazine, 27 Oct. 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