english
1
general::
Privy to special or secret information, as in Not too many people are in the know about this project. [Late 1800s]
American Heritage Idioms
2
general::
Phrase(s): in the know knowledgeable. • Let’s ask Bob. He’s in the know. • I have no knowledge of how to work this machine. I think I can get myself in the know very quickly though.
McGrawhill's American Idioms And Phrasal Verbs