(foggier, foggiest)
1.
When it is ~, there is fog.
Conditions were damp and ~ after morning sleet.
ADJ: oft it v-link ADJ
2.
If you say that you haven’t the foggiest or you haven’t the foggiest idea, you are emphasizing that you do not know something. (INFORMAL)
I did not have the foggiest idea what he meant...
PHRASE: V inflects emphasis