What does underground mean?
Underground describes anything located below the surface of the ground, and it can also mean something hidden, secret, or outside the cultural mainstream. Its transport sense refers to a railway running beneath streets and buildings, most famously the London Underground. As an adjective, noun, adverb, and less commonly a verb, the word has developed from a straightforward spatial description into a metaphor for concealed activity. Underground music, literature, economies, and political movements may exist beyond official or popular view, sometimes deliberately so. The word is therefore useful not only for discussing physical spaces but also for describing secrecy, marginality, and opposition to the mainstream. In American English, subway is generally preferred for the transport system, although underground remains common in other senses.
Located below ground or beneath the surface; concealed, secret, or outside the mainstream.
"The report revealed an underground network of tunnels."
When used of music, art, or other cultural activity, underground often implies independence from commercial or institutional mainstream culture.
An underground railway system, especially the London Underground; alternatively, a clandestine movement, network, or cultural scene.
"She took the Underground to avoid the heavy traffic above ground."
Capitalization is conventional for the London Underground. The plural form is uncommon, and references to a subway system are often phrased as an underground railway.
To place, move, or operate something beneath the ground.
"Engineers undergrounded the cable beneath the field."
This use is relatively uncommon compared with the adjective and noun senses.
Beneath the ground or below the surface.
"The tunnel continues underground for another several miles."
The adverb is often interchangeable with below ground or beneath the surface.
The plural is grammatically standard but uncommon; underground railway is often used when referring to more than one urban rail system.
"Several undergrounds serve the surrounding towns and suburbs."
The London Underground opened in 1863 and became the world's first underground urban railway, giving its name to a transport network used every day.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does underground come from?
Underground was formed in Middle English from the established elements under and ground. Its oldest uses referred to something physically below the earth's surface, while figurative senses for concealment developed naturally from that spatial idea. The transport sense arose during the nineteenth century with the construction of underground railways, especially in London, and was soon shortened to underground.
How underground is actually used
The word is common in both British and American English, though speakers in Britain more commonly call a subway an underground or the Underground, while American speakers usually say subway. In cultural contexts, underground often suggests secrecy, independence, and resistance to commercial or institutional mainstream culture.
Easily confused with underground
Underground means below the ground or concealed, whereas undergrowth means dense vegetation covering the ground.