'auntly' originates from English, specifically the word 'aunt' plus the adjectival suffix '-ly', where 'aunt' comes via Middle English from Old French (ante/tante) ultimately from Latin 'amita' meaning 'father's sister', and the suffix '-ly' derives from Old English '-lic' meaning 'like'.

'amita' (Latin) → 'ante'/'tante' (Old French) → 'aunte'/'aunt' (Middle English) → modern English 'aunt'; separately Old English '-lic' → Middle English '-ly' produced the adjectival form 'auntly'.

Initially 'aunt' referred specifically to a female relative (often father's sister); over time it generalized to the modern sense of 'a female relative of a parent', and 'auntly' came to mean 'like an aunt'—possessing aunt-like qualities (protective, indulgent, familiar).