Catching up on mbnov 15/11:

In Scots, the word murky is drumlie meaning 1. (of water) troubled, clouded, muddy; 2. (of weather) cloudy, gloomy; 3. troubled, muddled, confused.
Another word for murky is mirkie, meaning dark, dirty.
Mirkie can also mean merry, mischievous.

@SusanB I wonder if that’s where Middle-Earth’s Mirkwood comes from (or, rather, how the i got in there)?