1.
bullet; shot; round of ammunition
A bullet or projectile fired from a gun. When read 弾, the character refers to ammunition; the same character is read 弾 in compounds such as 弾丸 (bullet).
When read 弾, this character means a bullet or round of ammunition. The same sound is written 玉 (ball, sphere) or 球 (ball) for other senses — the 弾 spelling specifically signals ammunition.