I kept meaning to say that the Irish place name element “desert” ("díseart" in Irish), comes from “desertum” and indicates a hermitage, as in Desertegny, Donegal, “Díseart Eigne”, Egnagh’s hermitage, and Desertmartin, Derry, “Díseart Mhártain”, St Martin’s hermitage. According to Adrian Room’s Dictionary of Irish place-names, “díseart” “usually implies a secluded monastery, especially one with a strict rule”.
I have seen a suggestion - but can’t now find the reference - that the Irish took the “desert” element from St Anthony the Great and the other “Desert Fathers”, the earliest monks, who settled in the Egyptian deserts away from civilisation, but I believe this has been comprehensively rubbished, and the Irish used the name “desertum” simply because the areas they set up their hermitages/monasteries were just that, “deserted”, rather than as an homage to Anthony and the rest.