'aunty' originates from English, specifically the word 'aunt' with the diminutive/affectionate suffix '-y', where the suffix '-y' meant 'diminutive or affectionate'.

'aunt' changed from Old French word 'ante'/'aunte', which came from Latin 'amita', and eventually became the modern English word 'aunt' before the formation of the diminutive 'aunty'.

Initially the root (Latin 'amita') referred specifically to a 'paternal aunt'; over time it generalized to mean any sister of a parent or the wife of an uncle, and the diminutive 'aunty' developed as an affectionate or informal form and as a form of address.