Formal:
* Ignorant: This emphasizes a lack of knowledge.
* Unaware: This implies a lack of awareness or understanding.
* Uninformed: This suggests a lack of information.
* Unversed: This means lacking experience or familiarity with something.
* Naive: This implies a lack of worldly experience or sophistication.
Informal:
* Dumb: This is a more blunt and negative term.
* Lost: This implies a lack of direction or understanding.
* Out of the loop: This means being uninformed or excluded from something.
* Green: This refers to someone inexperienced.
* clueless: This means not understanding.
Other options:
* Uncomprehending: This implies a lack of understanding.
* Confused: This means not able to think clearly.
* Bewildered: This suggests being confused or puzzled.
* Disoriented: This means lacking a sense of direction or understanding.
The best word to use will depend on the specific situation and the tone you want to convey.