clueless
adj. B1 Intermediate US //ˈkɫuɫəs// UK //klˈuːləs// clue·less
adj. not knowing anything about a subject or situation. You use this when someone is completely unaware of what is happening.
adj. having no knowledge, awareness, or understanding of a particular matter. Often used with 'about' or 'of'.
I was clueless about the surprise party.
The manager remained clueless about the staff's growing frustration until the resignation letters arrived.
Despite the obvious warning signs in the market data, the board remained blissfully clueless about the impending financial crisis.
From clue + -less.