Term: bump stock
Definition: A device which, when attached to a semi-automatic firearm, increases its rate of fire to that of a fully automatic weapon.
Example (I didn't copy down sentences form the sources, this is my sentence): "Legislation on bump stocks is being discussed in Congress."
Sources: TV, every day on CNN; in print, The New York Times (Sat-Sun Oct 7-8; Tues Oct 10; Wed Oct 11); The Economist, issue of Oct 7...
Explanation: When attached to the gun's stock, the device bumps up (increases) its rate of fire.
"bump stocks" can be found on Google.
(In English Wikipedia, we read:"In firearms, bump fire is the act of using the recoil of a semi-automatic firearm to fire shots in rapid succesion, which simulates the ability of a fully automatic weapon.")
Title of an article in today's online Daily Kos: "Georgia Republicans Love Bump Stocks Used by Las Vegas Shooter". (It was the Las Vegas massacre that brought the term into everyday speech, and the existence of these devices and the slaughter they can wreak to public attention.)