foggy (adj.)youdaoicibaDictYouDict
1540s, of the air, "full of thick mist," perhaps from a Scandinavian source, or formed from fog (n.1) + -y (2). Foggy Bottom "U.S. Department of State," is from the name of a marshy region of Washington, D.C., where many federal buildings are (also with a suggestion of political murkiness) popularized 1947 by James Reston in "New York Times," but he said it had been used earlier by Edward Folliard of "The Washington Post."
murk (n)youdaoicibaDictYouDict
c. 1300, myrke, from Old Norse myrkr "darkness," from Proto-Germanic *merkwjo- (cognates: Old English mirce "murky, black, dark; murkiness, darkness," Danish mǿrk "darkness," Old Saxon mirki "dark"); cognate with Old Church Slavonic mraku, Serbo-Croatian mrak, Russian mrak "darkness;" Lithuanian merkti "shut the eyes, blink," from PIE *mer- "to flicker" (see morn). Murk Monday was long the name in Scotland for the great solar eclipse of March 29, 1652 (April 8, New Style).
murky (adj.)youdaoicibaDictYouDict
mid-14c., from murk + -y (2). Rare before 17c. Related: Murkily; murkiness.