noun
soaked to the skin; like a drowned rat
Idiomatic expression describing someone completely drenched, often from rain or falling into water. Used in phrases like 濡れ鼠になる.
突然の雨で、彼は濡れ鼠になってしまった。
He got soaked to the skin in the sudden rain.
川に落ちて、まるで濡れ鼠のようだ。
He fell into the river and looks just like a drowned rat.
ずぶ濡れ is a more common and direct way to say 'soaking wet', while 濡れ鼠 is a more vivid, idiomatic simile.
Compound of 濡れ (nure, 'soaked') + 鼠 (nezumi, 'rat/mouse'), literally 'soaked rat'. The exact origin is uncertain, but it is a traditional simile for a person drenched to the skin.