fug vs fog

fug and fog both are nouns.

Word	Noun	Adjective	Verb	Adverb
fug	Yes	No	No	No
fog	Yes	No	Yes	No

As nouns, fog is a hypernym of fug; that is, fog is a word with a broader meaning than fug:

fug: (British informal) an airless smoky smelly atmosphere
fog: an atmosphere in which visibility is reduced because of a cloud of some substance

Other hypernyms of fug include fogginess, murk, murkiness.

fug (noun)	fog (noun)
(British informal) an airless smoky smelly atmosphere	confusion characterized by lack of clarity
	droplets of water vapor suspended in the air near the ground
	an atmosphere in which visibility is reduced because of a cloud of some substance

fug (verb)	fog (verb)
	make less visible or unclear