WordNet sense 1 (flap consisting of a piece of canvas that can be drawn back to provide entrance to a tent):

rainfly, tent-fly, fly sheet, tent flap

WordNet sense 2 (an opening in a garment that is closed by a zipper or by buttons concealed under a fold of cloth):

fly front

WordNet sense 3 (run away quickly):

flee, take flight

WordNet sense 4 (pass away rapidly):

fell, vanish

WordNet sense 5 (fly a plane):

pilot, aviate

WordNet sense 6 (travel through the air; be airborne):

wing

WordNet sense 7 (decrease rapidly and disappear):

vaporize

WordNet sense 8 ((baseball) a hit that flies up in the air):

fly ball

WordNet sense 9 (very attentive or observant):

alert