sniper

A sniper is a shooter who fires accurately from hiding. A sniper's nest, sniper fire, a trained sniper.

The job is as much fieldcraft as marksmanship — moving unseen, waiting, judging wind and distance — and snipers work in pairs, with a spotter. The word came from snipe hunting: shooting snipe took such skill that a good shot was called a sniper. Figuratively, to snipe at somebody is to make small attacks from a safe distance, which keeps the image exactly.