(idiomatic) as it is already known.

A response used to indicate that speaker was in agreement with the preceding statement before it was made. / An emphatic assertion that one has a solution, an answer, or an idea.

Something that one needs to know; a piece of necessary information.

(idiomatic) (of information) given to another only when necessary.

(historical) The doctrines, principles, or practices of the Know-Nothings.

(historical) A member of a secret antiforeigner political organization in the nineteenth-century United States.

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

(idiomatic) Indicates agreement, approval, encouragement.

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

A rhetorical question asked to show that the person asking it neither knows the answer nor knows who might.