up in the air
Meaning: If something such as a plan to do something, or details of an agreement, are up in the air, they still haven't been decided or settled yet.
- The meeting will definitely take place, but details such as the venue and the date are still up in the air.
- The selection of players for the tour has been left up in the air until we get the results of their medical tests.
We'll have to leave the list of guests we're inviting to our wedding up in the air until we know