A sharpshooter is one who is highly proficient at firing firearms or other projectile weapons accurately.
So I guess I could qualify as a "sharpshooter" on a handgun, rifle, crossbow, air rifle, and longbow.
Some people think the term originated with the American Civil War, and skirmishers/snipers using Sharp's rifles. However, the term "sharp shooter", was in use in British newspapers as early as 1801. In the Edinburgh Advertiser, 23 June 1801, can be found the following quote in a piece about the North British Militia; "This Regiment has several Field Pieces, and two companies of Sharp Shooters, which are very necessary in the modern "Stile of War". The term appears even earlier, around 1781, in Continental Europe, translated from the German Scharfschütze.
As far as accuracy, the qualification varies.
https://en.wikipedia.org/wiki/Marksmanship_badges_(United_States)#U.S._Army