pressĭo, ōnis, f. [premo]. I.Lit., a pressing, pressing down, pressure (only in Vitruvius): pressio cacuminis, Vitr. 10, 8. —II.Transf., the prop or fulcrum under a lever while the burden is raised, Caes. B. C. 2, 9, 6: pressio, quod Graeci u(pomo/xlion appellant, Vitr. 10, 8.