Wiktionary
n. A maritime tool consisting of a weight (the "shot") affixed to the end of a long cord, used to cast line from one location to another and sometimes as an improvised weapon.
Wikipedia
A slungshot is a maritime tool consisting of a weight, or "shot," affixed to the end of a long cord often by being wound into the center of a knot called a " monkey's fist." It is used to cast line from one location to another, often mooring line. The cord end is tied to the heavier line and the weighted end of the slungshot is thrown across the intervening space where a person picks it up and pulls the line across.
Usage examples of "slungshot".
It was the rule that the man who was the readiest in the use of fist and slungshot at home had the greatest diffidence about forming a close acquaintance with cold lead in the neighborhood of the front.