Ignorant; characterized by foolish denial of facts or beliefs in that which is not true.

An ignorant person; one who lacks knowledge.

plural of know-nothing

present participle of know someone

(set phrase) To recognize that a statement or belief is false or doubtful. / (set phrase) To understand that certain behavior is wrongful, futile, or inappropriate.

Knowing of itself, or without the communication from another.

plural of Know-Nothing

Alternative form of you know what

(idiomatic) To have personal or social connections.

(UK, transitive) To have very thorough knowledge of.