A general term for any object that is thrown, launched, or otherwise propelled through the air, such as a bullet, arrow, or thrown stone.
The projectile flew at 200 kilometers per hour.
The police collected fragments of the projectile at the scene.
飛び道具 is a more traditional or colloquial term for projectile weapons or thrown objects, often used in historical or gaming contexts.
Compound of 投射 (とうしゃ, 'projection, throwing') and 物 (ぶつ, 'thing, object').