AFV - Armored fighting vehicle.

APDS - Armor piercing, discarding sabot; a type of ammunition consisting of a solid shot of smaller diameter than the bore of the gun which is attached to a sabot that makes up the difference in diameter until the shot leaves the gun, after which the sabot falls away. This arrangement leads to very high muzzle velocity of the shot, which means a flat trajectory (high accuracy) and high kinetic energy (penetration) at relatively short ranges.

APHE - Armor piercing, high explosive; a type of ammunition which depends on kinetic energy to achieve penetration but then explodes after penetration.

Glacis - The armor plate on the lower part of the hull at the front of an AFV.

HEAT - High explosive, anti-tank; a type of ammunition containing a shaped charge, like a bazooka. Its penetrating ability is constant regardless of the range to the target, since it depends on the charge, not kinetic energy.

Mach 7 - Seven times the speed of sound.

ROF - Rate of fire (number of shots per turn).

Smoothbore - A gun without rifling (spiral grooves) in the bore; rifling causes the shell to spin, which increases directional stability (accuracy) but decreases the penetrating power of HEAT.

Revisions and Notes on Modern Armor
Modernizing Those Modern Armor Rules
Main Battle Tanks, 1973