ra·dix \ˈrādiks\noun (pluralradi·ces \ˈradəˌsēz, ˈrād-\ ; orradixes \ˈrādiksə̇z\) Etymology: Latin, root — more at root 1.: base 6d < 10 is the radix of the common system of logarithms > 2.obsolete: root 4a 3.: the primary source : the originating cause 4.archaic: etymon, root 6 5.: the root of a plant 6.: radicle 2; especially: a root of a cranial or spinal nerve