don't-know
US /doʊntˈnoʊ/
UK /doʊntˈnoʊ/

1.
a person who is ignorant or undecided about something
:
•
He's a bit of a don't-know when it comes to politics.
•
The survey showed a high percentage of don't-knows regarding the new policy.
a person who is ignorant or undecided about something