Merriam-Webster Dictionary: Definition of Grinder  grinder: noun grind`er molar (teeth) one that grinds a machine or device for grinding an athlete who succeeds through hard work and determination rather than exceptional skill It’s about 6:15 at Rider Field in Frisco and game time is 7:05. Above the bench there is a Gatorade towel laid out with a hat, sunglasses, sunflower seeds …