Automatic pistol and Automatic weapon

Automatic pistol noun - A pistol that will keep firing until the ammunition is gone or the trigger is released.

Automatic weapon and automatic pistol are semantically related. In some cases you can use "Automatic weapon" instead a noun phrase "Automatic pistol".

Automatic weapon noun - A firearm that reloads itself and keeps firing until the trigger is released.

Automatic pistol and automatic weapon are semantically related. Sometimes you can replace phrase "Automatic pistol" with "Automatic weapon", this phrases are similar.