Shemhamforash

Shem HaMephorash (Hebrew: שֵׁם הַמְּפֹרָשׁ Šēm hamMəfōrāš, also Shem ha-Mephorash), meaning "the explicit name", was originally a Tannaitic term for the Tetragrammaton. Early sources, from the Mishnah to the Geonim, only use "Shem haMephorash" to refer to the four-letter Tetragrammaton. In the Rishonic period, the same term was reinterpreted to refer to a 42-letter name. and in Kabbalah, it may also refer to 22 or 72-letter names, the latter being more common.