“Where there are several co-obligants in one obligation, each bound in full performance, they are said to be liable singuli in solidum; and where each is liable only for his own proportion of the debt, they are said to be liable pro rata.” John Trayner, Trayner’s Latin Maxims 580 (4th ed. 1894).
singuli in solidum
singuli in solidum (sing-gy[schwa]-lI in sol-[schwa]-d[schwa]m). [Latin] Hist. Each for the whole.