noun
propellant; gunpowder charge
Technical term for the chemical substance that propels a projectile from a firearm or a rocket. Used in military, engineering, and firearms contexts.
発射薬の種類によって弾の初速が変わる。
The muzzle velocity of the bullet changes depending on the type of propellant.
ロケットの発射薬には固体燃料が使われることが多
Solid fuel is often used as the propellant for rockets.
推進薬 is a more general term for propellant used in rockets and spacecraft, whereas 発射薬 is more commonly associated with firearms and artillery.
Compound of 発射 (firing, launching) and 薬 (chemical agent, powder). The term is a straightforward technical coinage from the late 19th to early 20th century, when modern firearms terminology was standardized in Japanese.