The phrase "be midair" refers to an object or person that is suspended in the air, in a state of motion. The antonyms for this phrase include "grounded," "stationary," "settled," "stagnant," and "motionless." These words imply that the object or person is not in motion and is firmly fixed in place. Being stationary or grounded can also indicate a lack of progress or movement. Contrarily, some other words that could be considered antonyms for "be midair" include "descending" or "landing," indicating an object or person that is coming down from the air to the ground.