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one line; one stretch (e.g. of road); one strand (e.g. of hair); one beam (e.g. of light); one ray; one length (e.g. of rope)
earnest; resolute; intent; devoted; single-minded
彼女は一筋に夢を追い続けてきた。
She has single-mindedly continued to pursue her dream.
暗闘の中に一筋の希望の光が見えた。
I saw a ray of hope in the darkness.
この問題は一筋縄ではいかないね。
This problem isn't straightforward, is it?