'irregularity' originates from the Latin word 'irregularitas', where 'ir-' meant 'not' and 'regularitas' meant 'regularity'.

'irregularitas' transformed into the Old French word 'irregularité', and eventually became the modern English word 'irregularity'.

Initially, it meant 'not regular', but over time it evolved into its current meaning of 'lack of uniformity or consistency'.