'mediocrity' originates from Latin, specifically the Medieval Latin word 'mediocritas', where 'medi-' (from Latin 'medius') meant 'middle' and 'mediocris' meant 'moderate' or 'ordinary'.

'mediocrity' changed from Medieval Latin 'mediocritas' into Old/Middle French and then entered Middle English as forms like 'mediocrite', eventually becoming the modern English 'mediocrity'.

Initially, it meant 'middleness' or 'moderateness', but over time it evolved to include the more negative sense of 'lack of excellence' or 'ordinary/unremarkable quality' used today.