Basic Information
In modern usage, a single round of cased ammunition containing projectile(s), propellant and firing cap packaged and loaded as a single unit. The word can also apply to the casing that holds the round together (although this is more properly called the cartridge case) and which is usually called upon to serve additional functions such as sealing the breech on firing.
Previously a cartridge could also be a single round of powder and shot ammunition containing a pre-measured charge of propellant and a ball, wrapped together in paper (hence the term "cartridge paper" - a specific grade of paper, resilient enough for cartridge making).