noun, noun which may take the genitive case particle 'no'
underground; below the ground
Physical space beneath the surface; often used for subways, basements, and subterranean facilities. Antonym: 地上 (above ground).
Antonyms: 地上
The subway runs underground.
This building has an underground parking lot.
the grave; world of the dead
Metaphorical use referring to the realm of the dead; often in literary or fixed expressions.
He thought of the many war dead sleeping beneath the ground.
noun which may take the genitive case particle 'no', noun
underground (activities); secret; illegal
Describes covert, clandestine, or illegal operations, movements, or organizations.
They formed an underground organization and resisted.
They spread information through underground publishing.
This department store has a food section in its basement.
He lies buried in his hometown.
The organization continues to operate underground.
地下 is the generic word for 'basement/underground', whereas デパ地下 is a fixed colloquial term specifically for a department store's food floor.
underground lake; subterranean lake
underground stem; rhizome
groundwater; underground water
burying; underground installation; going underground
basement; cellar
dungeon; underground prison
underground wire; underground cable
underground station; subway station
underground publication; samizdat
underground activities; secret maneuvering
underground resistance
water table; groundwater level