'predictor' originates from Latin, specifically the verb 'praedicere,' where 'prae-' meant 'before' and 'dicere' meant 'to say.'

'praedicere' passed into Late Latin and Old French (e.g. 'predire'), then into Middle English forms related to 'predicen' and eventually became the modern English 'predict' and the agent noun 'predictor.'

Initially it meant 'to say beforehand,' and over time it evolved into the more general modern sense of 'to forecast' or 'to indicate in advance.'