'argilloarenaceous' originates from a combination of Neo-Latin combining form 'argillo-' (from Latin 'argilla' meaning 'clay') and English adjective 'arenaceous' (from Latin 'arenaceus' meaning 'sandy').

'argilla' in Latin gave rise to forms such as 'argillaceous' in English meaning 'clayey', while Latin 'arenaceus' produced English 'arenaceous' meaning 'sandy'; the compound 'argillo-' + 'arenaceous' was formed in technical/academic usage to denote material that is both clayey and sandy, yielding 'argilloarenaceous'.

Originally the elements referred separately to 'clay' and 'sand'; over time the compounded adjective came to specify mixtures or textures containing both components (current technical meaning: 'containing both clay and sand').