in the air—
1. not inside a house or building:
- We have taken our last walk in the air and having succeeded in tiring ourselves feel free to go to bed unashamed.
2. aboard an aircraft; in flight:
- After all, Short’s Empire class flying boats fifty years ago could offer a bed in the air.
3. (of plans, questions, etc.) still uncertain; remaining undecided:
- As for other ever changing events, next year’s plans are still in the air.
4. (also: in the wind) rumored or suspected but not definitely known:
- What changes they will make nobody knows, but there is something in the air.
5. said of the general mood or atmosphere:
- There was a feeling of joy in the air. Men who had never voted before said that they felt like human beings for the first time in their lives.
6. (of military position) uncovered or unprotected:
- This left the French First Army’s flank in the air, forcing it to withdraw as well.
Note: The expression does not fully correlate in meaning with the phrase in the open air—
1. = in the air 1:
- In the early evening Ernest went to speak to a group of the neighboring inhabitants in the open air.
2. unsheltered or unprotected from the elements:
- I myself saw new motors and parts piled up unprotected in the open air.
up in the air—
1. = in the air 2:
- If you’re up in the air and something goes wrong, you pull that parachute, and the whole plane goes down slowly.
2. = in the air 3:
- Our plans for a vacation are still up in the air, but we’ll be going sometime after the new year.
3. (coll.) angry; excited:
- He is all up in the air because he had to wait a few minutes.
Note: Neither expression correlates in meaning with the phrase on the air—
1. speaking over the radio:
- If Bucky Maynard doesn’t like you, you got a lot of trouble. I mean, he can destroy you on the air.
2. (of a program) being broadcast:
- McGannon is asking that stations be obliged to set aside a time when only children’s programs would be allowed on the air.