Shemhamphorasch
The Shemhamphorasch (alternatively Shem ha-Mephorash or Schemhamphoras, originally Shem HaMephorash (שם המפורש)) is an originally Tannaitic term describing a hidden name of God in Kabbalah (including Christian and Hermetic variants), and in some more mainstream Jewish discourses. It is composed of either 4, 12, 22, 42, or 72 letters (or triads of letters), the last version being the most common.
12-, 22-, and 42-letter versions
Maimonides thought the Shem ha-Mephorash was used only for the four letter Tetragrammaton.
A 12-letter variant appears in the Talmud, though it was unknown in later Kabbalah and completely absent from Jewish magic.
A 22-letter variant is first written down in Sefer Raziel HaMalakh, without interpretation, as אנקתם פסתמ פספסים דיונסים (likely transliterated as Anaktam Pastam Paspasim Dionsim). Its origins are unknown, with no connection to Hebrew or Aramaic being found, and no agreement on any particular Greek or Zoroastrian origin. There are Geonic precedents for the name, indicating that the name is older than Sefer Raziel.