This is the 13843rd most frequent Polish word.
poleciał
"Poleciał" means "he/it flew" or "he/it fell" depending on context.
In this sentence, 'poleciał' indicates the action of flight or movement through the air performed by the airplane.
Samolot poleciał nad miastem.
The airplane flew over the city.
Here, 'poleciał' is used to describe the unintentional motion or falling of the key due to gravity.
Mój klucz poleciał z balkonu na ziemię.
My key fell from the balcony to the ground.
In this usage, 'poleciał' refers to the movement or trajectory of the ball through the air toward a direction.