mudsill \ˈ ̷ ̷ˌ ̷ ̷\noun 1.: the lowest sill of a structure (as of a house, bridge, dam) usually embedded in soil or mud 2.: a person of the lowest stratum of society < a mudsill like me trying to push in and help — Mark Twain > < all classes and conditions of society from the millionaire to the mudsill — D.D.Martin >