Knowledgeable or having access to information about something, especially that which is exclusive or secret.

How do you use in the know?

In-the-know sentence example. We just want to be in the know . Dean paid no mind that the old man wasn't in the know about the latest Hollywood styles and so informed him.

What does it mean when your are in the know?

Meaning: If you are in the know, you have access to all the information about something, which other people don't have.