ROCK'-ALUM, noun The purest kind of alum. [See Roche-alum. ROCK'-BASON, noun A cavity or artificial bason cut in a rock for the purpose, as is supposed, of collecting the dew or rain for ablutions and purifications prescribed by the druidical religion.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI