The device which produces screengrabs. Literally, any combination of hardare and software used to get a still image from a TV signal or computer's video output into a digital file. In the capper vernacular the term has extended to include all and any of the hardware and software (and sometimes human) elements responsible for getting the image to be capped onto a capper's computer.
Screengrabbers are notorious for freezing up, sending out blank images, and otherwise messing up. It should be noted that with the advent of capping pre-grabbed images at sites like Inventing Situations (), Dementia 3000, and Glitter's Cap-Page Board and the death of capping images from live tv at sites like Caption This! at Inventing Situation's forerunner, cappers now have a level of insulation from the actual screengrabbers.