ignorant

Definitions
Examples

(noun): One who is ignorant.
(adjective): Unknowledgeable or uneducated; characterized by ignorance.
(adjective): Not knowing (a fact or facts), unaware (of something).
(adjective): Ill-mannered, crude.
(adjective): Unknown; undiscovered
(adjective): Resulting from ignorance; foolish; silly.

His manner was at best off-hand, at worst totally ignorant.