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

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

(idiomatic, dialect, slang) Indicates agreement, approval, encouragement.

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

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

(idiomatic, vulgar, followed by a wh-clause) I don't know; nobody knows; it is unclear.

It is only known to God; it is unknown to people. / (often modifying a parenthetic concession) It is known unto God; it is certainly true.

(informal, idiomatic) Despite the addressee's belief that the speaker was unaware of something, the speaker, in fact, was already aware.

(idiomatic) Indicates agreement, approval, encouragement.

(transitive) To become acquainted with (someone or something); to meet someone. / Used other than figuratively or idiomatically: see get, know.