SOLIDUS

n. (pl. solidi) 1 an oblique stroke (/) used in writing fractions (3/4), to separate other figures and letters, or to denote alternatives (and/or) and ratios (miles/day). 2 (in full solidus curve) a curve in a graph of the temperature and composition of a mixture, below which the substance is entirely solid. 3 hist. a gold coin of the later Roman Empire. [ME (in sense 3) f. L: see SOLID]