not have the faintest/foggiest

not have the foggiest

To have no knowledge or understanding whatsoever about something. He doesn't have the foggiest how hard it is to run a business. A: "Do you know where the car keys are?" B: "I don't have the foggiest. Sorry."
See also: foggy, have, not
Farlex Dictionary of Idioms.

not have the faintest (idea)

have no idea. informal
See also: faint, have, not

not have the foggiest (idea or notion)

have no idea at all. informal, chiefly British
See also: foggy, have, not
Farlex Partner Idioms Dictionary

not have the ˈfaintest/ˈfoggiest (idea)

(British English, informal) have no idea at all about something; not know anything at all: I haven’t got the faintest idea what to buy Roger for his birthday. ‘Where are we?’ ‘I’m afraid I haven’t the foggiest.’
See also: faint, foggy, have, not
Farlex Partner Idioms Dictionary
See also:
  • not have the foggiest
  • not have the foggiest notion
  • (one) hasn't the foggiest
  • foggy
  • hadn
  • not have the foggiest idea
  • the foggiest idea
  • foggiest
  • the foggiest understanding
  • have a working knowledge of something