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the vertical; height
front-to-back; length
north-to-south
vertical (relationship); hierarchy
(weaving) warp
「経」 has other readings with different meanings.
経に線を引いてくださいね。
Please draw a vertical line.
この布は経と横がありますよ。
This fabric has a warp and weft.
経に切った方がきれいに仕上がると思います。
I think cutting it vertically will give a nicer finish.