adverb
Mimetic adverb describing something being wet or damp, often with a sense of being thoroughly or unpleasantly wet. Used with verbs like 濡れる, 湿る, or なる.
雨で服が濡れ濡れになった。
My clothes got all wet from the rain.
汗でシャツが濡れ濡れだ。
My shirt is soaking wet with sweat.
Reduplication of the stem 濡れ (from 濡れる, 'to get wet'), forming a mimetic adverb. The exact origin is uncertain, but it follows a common pattern for Japanese onomatopoeic/mimetic words.