'atopy' originates from Greek, specifically the word 'atopia', where 'a-' meant 'not' and 'topos' meant 'place' (giving the sense 'out of place' or 'strangeness').

'atopy' came into English from Greek via Medieval/Modern Latin and 19th-century medical usage; the Greek term 'atopos' ('out of place, strange') was adapted into scientific vocabulary and became English 'atopy'.

Initially it referred to 'strangeness' or 'inexplicability'; over time it acquired a medical sense of an inherited tendency toward allergic reactions (the current primary meaning).