foggy
adjective /ˈfɒɡi/
  /ˈfɑːɡi/
 (comparative foggier, superlative foggiest)
Idioms - not clear because of fog
- foggy conditions
 - a foggy road
 - He was driving much too fast for the foggy conditions.
 
Oxford Collocations DictionaryFoggy is used with these nouns:- idea
 - morning
 - night
 - …
 
Word Originlate 15th cent. 
Idioms 
not have the foggiest (idea) 
- (informal) to not know anything at all about something
- ‘Do you know where she is?’ ‘Sorry, I haven't the foggiest.’