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evaporation
disappearance (of a person); vanishing without a trace
水が蒸発して雲になる仕組みを理科で学んだよ。
I learned in science how water evaporates and becomes clouds.
蒸発した水分は雨となって地上に戻ってくるね。
Evaporated water returns to the ground as rain.
父が蒸発して家族に連絡がつかなくなったそうだ。
I heard the father disappeared and can't be contacted by family.