backshooter
nounEtymology From backshoot + -er.
1
US A cowboy who kills someone by shooting them in the back
- It would be so easy for Jed to jerk his rifle from its sheath, lever a cartridge into the firing chamber and put a bullet right between Colter's shoulder blades. For a fleeting moment, Jed considered doing just that. But he knew he was not a backshooter and more than that, he wanted to see the truth of the murder in Colter's eyes and make him squirm before dying at the end of a rope...2007, Jory Sherman, Abilene Gun Down, page 29:
2
Broadly A treacherous person