'apriority' originates from the Latin phrase 'a priori', where 'a' (from Latin 'ab'/'a') meant 'from' and 'prior' meant 'former'; English formed the noun by combining that phrase with the suffix '-ity' (from Latin '-itas').

'apriority' was coined in philosophical English by treating the Latin phrase 'a priori' as a base and adding the noun-forming suffix '-ity' (from Medieval/Latin '-itas'), producing the modern English noun 'apriority'.

Initially it meant 'the condition of being prior (earlier) or prior to experience'; over time it came to mean specifically 'the quality of being knowable or justifiable independently of experience' in philosophical contexts.