in on(redirected from let someone in on something)
in on (something)
Participating or involved in something, often something secret or exclusive. The conspiracy ran deep, and several members of the administration were in on it. Wow, that really was a surprise. Were you in on planning this?
*in on something
1. involved with something, such as an organization or an idea; informed about special plans. (*Typically: be ~; come ~; get ~; let someone ~.) There is a party upstairs, and I want to get in on it. I want to get in on your club's activities. Mary and Jane know a secret, but they won't let me in on it.
2. receiving a share of something. (*Typically: be ~; Come ~; get ~; let someone ~.) I want to get in on the new European business that is supposed to develop. We will all want to get in on the scheme.
Informed about; participating in: Only one business partner was not in on the illegal scheme.