plinthis, ĭdis, f., = plinqi/s (a square tile). I.A square; in architect., a square base, a plinth, for plinthus, Vitr. 3, 3, 2; in land-surveying, for plinthus, Hyg. Condit. Agror. p. 210 Goes.—II.Plur.: plinthĭ-des, a register in the hydraulic organ, Vitr. 10, 8, 8; v. pleuritis.