'argilloid' originates from Latin, specifically the word 'argilla,' where 'argilla' meant 'clay,' combined with the Greek-derived suffix '-oid' (from Greek '-oeidēs') meaning 'form' or 'resembling'.

'argilla' (Latin) was used in Medieval and New Latin scientific vocabulary as 'argill-' and was later combined with the suffix '-oid' in modern English technical coinages to form 'argilloid'.

Initially it referred simply to 'clay' or 'clay-related' material; over time it came to denote specifically things that are 'clay-like' or composed of clay (e.g., clay-like rocks or sediments).