A relatively small artillery piece designed to be used by infantry forces for the specific purpose of destroying enemy armored vehicles.  An example being the WWII German "Pak" anti-tank gun series.

Tag does [i]not[/i] apply to anti-tank_rifles, handheld anti-tank weapons such as bazooka/panzerfaust type weapons, or mechanized anti-armor support weapons such as the WWII German "Stug" series.
anti-tank gun