'baetylic' originates from Latin, specifically the word 'baetylus', which in turn was borrowed from Greek 'baitylos' (βαῖτυλος), referring to a sacred stone.

'baitylos' (Greek) became Latin 'baetylus', was used in Late Latin and Medieval Latin to denote sacred stones, entered English as 'baetyl' (noun), and the adjective form 'baetylic' was formed in modern English to mean 'relating to a baetyl'.

Initially it referred specifically to the stone itself ('sacred stone'), but over time the sense extended to describe things relating to or resembling such stones (i.e., sacred, cultic, numinous qualities).