rhythm game (genre of video game)

musicology

light music (such as popular songs, jazz, chanson, etc.), as opposed to classical music / semiclassical music

band (almost always a brass band formed from members of bodies such as the military or police)

underground water

underground line, specifically an underground cable or wire

dungeon

(AmE) subway; (BrE) underground; (BrE) tube

department store's below-ground-level food section

Synonym of 研究室 (kenkyūshitsu, “laboratory”)