Semi-automatic weapons - Authoritarians who oppose civilian gun ownership often use this term when speaking about firearms in order to make AR-15's and pistols (and perhaps even all firearms) seem sinister.
The reality is that a 'semi-automatic weapon' is defined as any gun that fires one round per trigger pull and automatically loads the next round into the chamber, such that the shooter can fire another shot with no action other than another squeeze of the trigger.
Pathetic, misinformed media companies like CNN and USA Today fail to mention that every gun in existence fits the description of semi-automatic except for very few types of guns, most of which are antiquated.
Examples of semi-automatics
DA revolvers (technically)
Examples of non-semi-automatics
Antique single-action-only revolvers