Aprojectile is a projectile is defined as:

A projectile is defined as, Defenition 1: a(n) object fired from a gun with a(n) explosive propelling charge, such as bullet, shell, rocket or grenade. Definition 2: a body projected or impelled forward, as through the air. Hope that helped, had to whip out my trusty dictonary for the first one. LOL.

A projectile is an object that once anticipated or dropped proceeds in movement by its own inertia and is affected just by the descending power of gravity.

For example,  you throw the ball straight upward and give them initial energy,It will on the earth making a projectile or parabola, because force of gravity acts downward force on it. Making it to follow the semi circular path.