haven't got a clue

Related

cluelessLacking any understanding
baffledUtterly unable to understand
confusedUnable to understand
lostUnable to navigate
stumpedUnable to solve

puzzled · bewildered · blank · mystified · perplexed · oblivious · ignorant · dunno · shrug · scratching · head · foggy · murky · drawing · blindfolded · guessing · grasping · straws

Opposites

knowledge/understanding

haven't got a clueknow inside and out

Understand something exhaustively

see clearly · know the score · be aware

competence/capability

haven't got a clueknow the ropes

Understand how things work

know one's stuff · know the drill

Familiarity: Top 2,000,000