adv. or adj. phr. 1. In the air; while flying. The duck flew away, but John shot it on the wing. 2. informal In constant motion; always very busy. Susan was on the wing doing things to get ready for her trip. Mr. Jones had a busy schedule and his secretary had to catch him on the wing to sign the letters.
Synonym: ON THE FLY. 3. informal Moving from one place to another; traveling; going somewhere. Mary's husband is a traveling salesman and he's always on the wing. They stayed in France for a week and then they were on the wing again.
Synonym: ON THE GO, ON THE MOVE.