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
However, Honer said the project features a subterranean parking garage as well as a surface parking lot, amounting to 75 spaces.
—
Tyler Faurot, San Diego Union-Tribune, 8 Jan. 2026
The Conch Bar Caves, on Middle Caicos, are among the biggest subterranean systems, a sinuous network festooned with stalactites and stalagmites.
—Henry Wismayer, Travel + Leisure, 7 Jan. 2026
The utility has a subterranean network of some 4,600 miles of pipes under the city, including significant stretches of original cast and ductile iron — some dating back to the 1800s — which pose a risk of gas leaks that could lead to an explosion.
—Robert Channick, Chicago Tribune, 6 Jan. 2026
Of course, the collective memory of the city, and its residents, can take irregular, even subterranean, forms.
—Matthew Specktor, HollywoodReporter, 5 Jan. 2026
See All Example Sentences for subterranean
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Tyler Faurot, San Diego Union-Tribune, 8 Jan. 2026
The Conch Bar Caves, on Middle Caicos, are among the biggest subterranean systems, a sinuous network festooned with stalactites and stalagmites.
—Henry Wismayer, Travel + Leisure, 7 Jan. 2026
The utility has a subterranean network of some 4,600 miles of pipes under the city, including significant stretches of original cast and ductile iron — some dating back to the 1800s — which pose a risk of gas leaks that could lead to an explosion.
—Robert Channick, Chicago Tribune, 6 Jan. 2026
Of course, the collective memory of the city, and its residents, can take irregular, even subterranean, forms.
—Matthew Specktor, HollywoodReporter, 5 Jan. 2026
See All Example Sentences for subterranean
Cite this Entry
“Subterranean.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/subterranean. Accessed 10 Jan. 2026.
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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