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ancestor; forefather; foremother
先祖を敬うことは日本の伝統文化だ。
Respecting ancestors is part of traditional Japanese culture.
お盆には先祖の墓参りをする習慣がある。
There's a custom of visiting ancestors' graves during Obon.
先祖代々この土地に住んでいるそうだ。
I heard they've lived on this land for generations.