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one long cylindrical thing; one film, TV show, etc.; one goal, home run, etc.; one telephone call
one version
one book; a certain book
ippon; one point; a blow
geisha
single-minded focus on ...
彼は一本勝ちで試合を決めた。
He won the match with an ippon.
見事な投げ技で一本を取った。
He scored an ippon with a great throw.
一本の映画を見終わった。
I finished watching a movie.