'probability' originates from Latin, specifically the word 'probabilitas' (from 'probabilis'), where the root 'probare' meant 'to test, to prove.'

'probability' changed from Late Latin 'probabilitas' and Old French 'probabilité' into Middle English and eventually became the modern English word 'probability'.

Initially it meant 'the quality of being probable or credible'; over time it broadened to include a mathematical sense as 'a numerical measure of likelihood'.