(chiefly UK, Ireland) Someone who obnoxiously claims to be knowledgeable on a subject.

plural of know-it-all

Knowing everything; omniscient.

plural of know-all

(ditransitive) To inform (someone) (of something).

Alternative form of God knows

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.

(idiomatic) as it is already known.

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

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