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to wither (of flowers, dreams, etc.); to wilt; to droop; to shrivel; to fade (away); to sag; to deflate
水をやらないと日が経つと花がしぼむ。
If you do not water them, flowers will wither as days pass.
計画が失敗して長年の夢がしぼんでしまった。
I failed and my dreams have faded away.
ゴム風船が空気が抜けてしぼんだ。
The rubber balloon deflated as air escaped.