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 ) ( subterrane ) + -an

Example Sentences

But you sense subterranean levels of weirdness that hint that he’s already got ideas for a sequel.

From Los Angeles Times • Jan. 25, 2026

Mr Hughes used to live in the Italian city of Florence where subterranean bins are common and he says they are widely used in most of western Europe.

From BBC • Nov. 15, 2025

Other subterranean tremors acknowledge Maia’s inner tug of war between New York and her new battleground.

From Salon • Nov. 2, 2025

Engineers had to design a well casing that could handle the subterranean inferno.

From The Wall Street Journal • Oct. 29, 2025

The vault opened onto one of the tunnels the brothers called the wormwalks, winding subterranean passages that linked the keeps and towers of Castle Black under the earth.

From "A Clash of Kings" by George R.R. Martin