A complete unit of assembled ammunition, including the case, propellant powder, primer, and bullet. The term is commonly applied only to rifle and pistol ammunition, but it is technically correct for shotshells as well.
A cartridge without a projectile is called a blank. One that is completely inert (contains no active primer and or propellant) is called a dummy. One that failed to ignite and launch the projectile is called a dud, and one that ignited but failed to sufficiently push the projectile out of the barrel is called a squib.
The Cartridge Comparison Guide shown above is available on Amazon.