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

Mulch most likely attracts subterranean termites by keeping the soil underneath cool and damp, which is ideal for tunneling. —Brandee Gruener, Southern Living, 4 Mar. 2026

Within our apartment’s small, semi-subterranean living room, my roommates and I set up a drum kit and a couple of guitar amps, and opened our doors to friends, neighbors, and strangers alike. —Taran Dugal, New Yorker, 4 Mar. 2026

Here are two more stories of the subterranean, one sinister and one salty. —Maureen O'Hare, CNN Money, 21 Feb. 2026

Their translucent bodies suggest adaptation to a subterranean environment where light doesn’t reach. —Hanna Wickes, Miami Herald, 20 Feb. 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