adj. or adv. phr. 1. informal In great anger or excitement. My father went straight up in the air when he heard I damaged the car. The Jones family are all up in the air because they are taking a trip around the world.
Compare: HIT THE CEILING, BLOW A FUSE. 2. also in midair Not settled; uncertain; undecided. Plans for the next meeting have been left up in the air until Jane gets better. The result of the game was left hanging in midair because it rained before the finish.
Compare: LEAVE HANGING.