a grigri is a securing device for rock climbing. unlike many other securing devices, a grigri is half-automatic. it works like a seat belt in a car. the rope can be slowly pulled through, but if there is lot of weight on the rope the grigri locks the rope. "grigri" is a trademark of the company petzl, but because it was the first half-automatic securing device, many people call devices of other companies also grigri.