From Longman Dictionary of Contemporary Englishundergroundun‧der‧ground1 /ˈʌndəɡraʊnd $ -ər-/ ●●○ adjective 1 UNDER/BELOWbelow the surface of the earth an underground passage The car park is underground.2 [only before noun]SECRET an underground group, organization etc is secret and illegal an underground terrorist organization► see thesaurus at secret3 [only before noun] underground literature, newspapers etc are read by a small number of people, and would seem slightly strange or shocking to most people the underground press
Examples from the Corpusunderground• The office's parking garage is underground.• Also, underground conditions were significantly different from what was anticipated.• But instead he returned to Hue as an organizer for an underground movement.• an underground newspaper• underground nuclear testing• Slowly an underground resistance movement grew, catering for discriminating customers.• If it is chosen, the underground site could start receiving canisters of waste in 2010, Olds said.• A private consortium has financial backing for a scheme to build an entire underground toll-road system.• The gas, which seeps out of the earth from underground uranium deposits, can collect in dangerous concentrations in some houses.• Amplification of this energy promotes fertilization of the surrounding area via underground water-courses.undergroundun‧der‧ground2 /ˌʌndəˈɡraʊnd $ -ər-/ adverb 1 UNDER/BELOWunder the earth’s surface This animal spends most of its life underground. nuclear waste buried deep underground2 → go underground
Examples from the Corpusunderground• Of this amount, about 30 percent can be mined at the surface; the balance is underground.• The industry is now investigating sites in which to dump nuclear waste underground.• Three of the stations are underground, and the last two at surface level.• Over the next few days, though, the signs of what was happening underground became more severe.• There is now a through route underground between Gaping Gill and Ingleborough Cave but only for brave men.• The insect spends most of its life underground, eating roots and stems.• Dining: Restaurants are open in the visitor center and underground, near the Big Room.• When he was making an underground survey of the New Almaden mine he stayed underground for twenty hours at a stretch.deep underground• After 50 years the waste will probably be buried deep underground.• Darkness seemed to engulf them as they disappeared, swallowed up in a kind of tunnel way, running deep underground.• Nervous trembles ached in her legs and the floor was vibrating fractionally with the movement of some train deep underground.• Rivers have been restored to healthy levels and, more importantly, this rain is at last reaching the water-permeable rocks deep underground.• Until now it was assumed that sites deep underground provided a stable environment for buried waste.• A notice informed the public that this was the deepest Underground station in London, three hundred stairs to the bottom.undergroundun‧der‧ground3 /ˈʌndəɡraʊnd $ -ər-/ noun → the Underground
Examples from the Corpusunderground• A desire to remind Rome of its arrogance remained latent in the Celtic underground.• His father, Wei Zilin, worked in the Communist underground in the 1930s.• No way do the charts tell the whole story - the new underground is of much more interest and relevance.• I found that I was a natural boss of a prison underground.• But the scale of recruitment to the revolutionary underground suggests that it can not be explained in terms of individual maladjustment.• But out of necessity, the underground continued to flourish.