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
That paragraph distills, with humming intensity, a central activity of this era, of the subterranean lives of people who stay up all night on Adderall and adrenaline.
—
Niela Orr, Vulture, 13 Jan. 2026
Unlike crude oil, which pools in subterranean reservoirs, shale oil is found within shale rocks.
—Stefanie Waldek, Space.com, 12 Jan. 2026
Spa Not content with growing sideways, Claridges has also dug deep—120 feet to be precise—to impress guests with its gorgeous, 7,000 square-foot subterranean spa.
—Condé Nast, Condé Nast Traveler, 11 Jan. 2026
Peoples 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, 9 Jan. 2026
See All Example Sentences for subterranean
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Niela Orr, Vulture, 13 Jan. 2026
Unlike crude oil, which pools in subterranean reservoirs, shale oil is found within shale rocks.
—Stefanie Waldek, Space.com, 12 Jan. 2026
Spa Not content with growing sideways, Claridges has also dug deep—120 feet to be precise—to impress guests with its gorgeous, 7,000 square-foot subterranean spa.
—Condé Nast, Condé Nast Traveler, 11 Jan. 2026
Peoples 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, 9 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 19 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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