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underground; below the ground
world of the dead; the grave
underground (activities, movement, etc.); secret; illegal; in hiding
地下鉄で通勤している人が多い。
Many people commute by subway.
戦没者の慰霊祭では、参列者が地下に眠る友の霊に静かに手を合わせ、長い黙祷を捧げた。
At the memorial service for the war dead, those gathered quietly joined their hands toward the spirits of friends asleep in the grave, and offered a long silent prayer.
地下室に荷物を保管しているよ。
I store my luggage in the basement.