plinth (n.)

"flat, square table or slab under the molding of the base of a Roman column; square molding at the base of any architectural part," 1610s, from French plinthe (16c.) and directly from Latin plinthus, from Greek plinthos "brick, squared stone," from PIE *splind- "to split, cleave," from root *(s)plei- "to splice, split" (see flint).