'baitylos' originates from Ancient Greek, specifically the word 'βαίτυλος' (baitylos); the form is likely related (perhaps via borrowing) to a Semitic compound like 'bet' + 'el' meaning 'house of god'.

'baitylos' entered Latin as 'baetylus' and Old Latin/medieval usage continued the sense of a sacred or fallen stone; earlier still the term likely reflects a Semitic-mediterranean religious vocabulary (e.g. Phoenician 'betyl' or similar), which influenced the Greek form.

Initially it referred specifically to a stone believed to have fallen from the sky and regarded as sacred; over time the sense broadened to include various sacred or cult stones and, in modern scholarly use, any ancient venerated stone.