The Sabian name is the period’s umbrella for star-worship traced back to the ancient Near East, and Adams’s own entry already points the reader on to the Mendai, the ambiguity the archive keeps in view.
In Hannah Adams
In Adams’s own words, from the 1817 Dictionary. Each passage is quoted verbatim under its own entry.
Sabeans, or Sabians, ancient inhabitants of Arabia, who worshipped the hosts of heaven (in Hebrew, Sabbaoth), though at the same time they acknowledged a supreme Being, by whom they were created. See Zabians.
A sect in Ecclesiastical History are called by the same name, whose creed is a compound of Judaism, Christianity, and Idolatry. See Mendai.
Zabeans, a name given to the Chaldeans, Persians, and other ancient Idolaters, who worshipped the Host of Heaven, and pretended to the arts of Astrology and Necromancy. See Sabeans.
Mendai, or Mendaeans, otherwise called Christians of St. John, or Hemero-Baptists, which see. These ambiguous Christians (says Mosheim) dwell in Persia and Arabia, and principally at Bassora, and their religion consists in bodily washings, performed frequently and with great solemnity.
Hannah Adams, A Dictionary of All Religions (Boston, 1817), entries “Sabeans,” “Zabeans,” and “Mendai.”