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

• belowground
• subsurface
• underground

Examples of subterranean in a Sentence

a subterranean bunker that supposedly could withstand even an atomic blast

Recent Examples on the Web

But if classic English weather rolls through, retreat to the subterranean spa, one of the hotel’s newest highlights. —Katie Lockhart, Travel + Leisure, 13 Oct. 2024

Something is genuinely off about the goings-on at the conference, from strange deaths and elevators that suddenly aren’t elevators, to a rash of scabby infections afflicting guests and the discovery of a subterranean tunnel. —Robert Abele, Los Angeles Times, 11 Oct. 2024

But no area embodies this color trend more than the subterranean media room, designed by Batliboi Studio. —Juliet Izon, Architectural Digest, 27 Sep. 2024

Additionally, the icy world may be hiding a subterranean sea of liquid water that’s roughly ten times deeper than Earth’s oceans. —Shi En Kim, Smithsonian Magazine, 5 Sep. 2024

Word History

Etymology

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

First Known Use

1603, in the meaning defined at sense 1

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