'precursory' originates from Latin, specifically the word 'praecursor', where 'prae-' meant 'before' and the root from 'currere' meant 'to run'.

'precursory' developed via Late Latin/Medieval Latin forms such as 'praecursorius' and the noun 'praecursor' ('one who runs before'), and entered English in forms derived from these Latin antecedents to yield the adjective 'precursory'.

Initially it referred to 'one who runs before' or a 'forerunner'; over time it broadened to the adjective sense 'coming before and indicating what will follow' (a preliminary sign or occurrence).