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.
Examples of subterranean in a Sentence
a subterranean bunker that supposedly could withstand even an atomic blast
Recent Examples on the Web
Unable to plausibly explain to the authorities what happened — or why she’s covered in her friends’ blood — Sarah is forced back to the subterranean depths to help locate her five missing companions.
—
Caitlin White, Variety, 3 Oct. 2025
While a few worlds in the Milky Way are believed to have liquid water hiding beneath a frozen surface, Enceladus isn't quite as secretive about its subterranean ocean.
—Eric Lagatta, USA Today, 3 Oct. 2025
The aim is to reduce evacuation zones and improve forecasting of risks to people, buildings, and subterranean infrastructure.
—Kaif Shaikh, Interesting Engineering, 1 Oct. 2025
Even though the house is long gone, I was allowed to walk through its subterranean lower levels and could vividly imagine families hiding in the storage areas.
—Literary Hub, 30 Sep. 2025
See All Example Sentences for subterranean
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Caitlin White, Variety, 3 Oct. 2025
While a few worlds in the Milky Way are believed to have liquid water hiding beneath a frozen surface, Enceladus isn't quite as secretive about its subterranean ocean.
—Eric Lagatta, USA Today, 3 Oct. 2025
The aim is to reduce evacuation zones and improve forecasting of risks to people, buildings, and subterranean infrastructure.
—Kaif Shaikh, Interesting Engineering, 1 Oct. 2025
Even though the house is long gone, I was allowed to walk through its subterranean lower levels and could vividly imagine families hiding in the storage areas.
—Literary Hub, 30 Sep. 2025
See All Example Sentences for subterranean
Cite this Entry
“Subterranean.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/subterranean. Accessed 16 Oct. 2025.
Copy CitationKids 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
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