subterranean

American  

[suhb-tuh-rey-nee-uhn] / ˌsʌb təˈreɪ ni ən /

adjective

1. existing, situated, or operating below the surface of the earth; underground.

2. existing or operating out of sight or secretly; hidden or secret.

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noun

1. a person or thing that is subterranean.

2. a subterrane.

subterranean British  

/ ˌsʌbtəˈreɪnɪən /

adjective

1. Also: subterraneous.   subterrestrial.  situated, living, or operating below the surface of the earth

2. existing or operating in concealment

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Other Word Forms

• subterraneanly adverb
• subterraneously adverb

Etymology

Origin of subterranean

1595–1605; < Latin subterrāne ( us ) ( see subterrane) + -an

Explanation

Subterranean is an adjective that describes something just below what can be seen, like the subterranean jealousy you hide under a smile and kind words for the actor who got the part you wanted. Subterranean feelings and intentions are those you keep "on the down low." In fact, real things that are subterranean really are down low — underground, in fact. A subterranean worm lives under the earth's surface. A subterranean lair is a secret hideout dug under the dirt — or maybe it's just your basement. The word comes from the Latin subterraneus, from sub meaning "under" and terra meaning "earth."

Example Sentences

There were root nematodes, launching a subterranean attack.

From Slate • Apr. 20, 2026

Located between the Sahara tent and the Do Lab, the Bunker is a gigantic subterranean cavern with room for 300 or so people — a dark and cool respite from the blazing Indio sun.

From Los Angeles Times • Apr. 10, 2026

Operating theatres, intensive care units and even maternity wards have been relocated to protected subterranean spaces.

From Barron's • Apr. 10, 2026

Engineers with excavating equipment would be needed to dig through the tons of debris blocking entrances to Iran’s subterranean nuclear complexes and check for mines and booby traps.

From The Wall Street Journal • Mar. 15, 2026

By elevator he descended to Polokov’s floor, found the hall unlit, like a subterranean cave.

From "Do Androids Dream of Electric Sheep?" by Philip K. Dick