Foggy
late 15th century: perhaps from fog2.
wiktionary
From fog + -y, originally in the sense "covered with tall grass; marshy; thick". [1] It is not clear whether fog(“mist”) is a back-formation from foggy(“covered with tall, obscuring grass”) [2] or has a separate Germanic origin, [3] and hence whether foggy(“covered with tall grass”) and foggy(“obscured by mist”) represent one word or two. See fog ("mist"; "tall grass") for more.
etymonline
foggy (adj.)
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 the New York Times, but he said it had been used earlier by Edward Folliard of The Washington Post.
