mudsill Posted in M Best definition mudsillsports Uneducated, working class. Low-life, thoroughly disreputable person. Kip: Baseball is for low life, aggro, retards. Jim: Yeah. Baseball fans are total mudsills. How satisfied are you with the definition? Looking for mudsill meaning? Delighted that you discovered the greatest determine on our web site! Recently this definition was actually observed 64 times.