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

An ignorant person; one who lacks knowledge.

(idiomatic) Indicates agreement, approval, encouragement.

(chiefly US, derogatory) Someone who claims to be knowledgeable or an expert in something, obnoxiously dismissing the opinions, advice, suggestions, etc. of others.

(informal) To be aware of a situation, especially of the consequences of misconduct.

The knowledge and skill to be able to (do something correctly).

Used other than figuratively or idiomatically: see you, know. / (informal) Expression signifying a pause or hesitation.

(idiomatic) To have personal or social connections.

Knowing of itself, or without the communication from another.

(also philosophy) Be aware of your own strengths and limitations.