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origin; birthplace
descent; lineage; ancestry; stock
その言葉の出自を調べてみたい。
I want to look into the origin of that word.
出自が不明な資料だ。
It's a document of unknown origin.
彼の家系の出自は東北地方にさかのぼる。
His family's origins trace back to the Tohoku region.