[roveo]

I imagine this word should be of Indoeuropean origin, Eastern Slav words for a mill also contain m-l-n (e.g. melnitsa).

Modern English lost the "n" part, but it was present in Middle English, milne.

[ivanhoe]

yes, it's "mlin" or "mlyn" in a number of Slavic languages, and I just looked up it's etymology in Serbian and the book says it comes from old slavic "mъlinъ" which they say comes from the Latin root "molinum"