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eye of a needle
hole
「穴」 has other readings with different meanings.
針の穴に糸を通すのが苦手だ。
I'm not good at threading a needle.
老眼で針の穴がよく見えなくなった。
My farsightedness has made it hard to see the eye of a needle.
糸通し器を使えば小さな穴にも簡単に糸が通せる。
With a needle threader, you can easily pass thread through even a small eye.