underground

Definition

Below the ground; below the surface of the Earth.

Etymology

From Middle English undergrounde (adverb), equivalent to under + ground or under- + ground. Compare Dutch ondergrond, ondergronds, German Untergrund, Danish undergrunds.

Example Sentences

• "There is an underground tunnel that takes you across the river."
• "One of the hidden glories of Victorian engineering is proper drains. Isolating a city’s effluent and shipping it away in underground sewers has probably saved more lives than any medical procedure except vaccination."
• "These criminals operate through an underground network."