The name is how the Amanyar called the Ring of Doom in Quenya. It contains the word Máhan "chief Vala".. All in all, it is said to be derived from Valarin Mâchananaškad.
Quenya
máhanaxar
place name. Ring of Doom, *(lit.) Ring of Judgement
máhanaxar
Máhanaxar
The circle of thrones where the Valar sat in council (S/38), an adaptation of the Valarin word Māχananaškād “Doom-ring” (WJ/399, 401). The Valarin word māχan more accurately means “authority, authoritative decision” (WJ/399), so the “doom” in its English translation is most likely used in its older sense “judgement”. This circle is also known by the (Vanyarin?) name Rithil-Anamo, said to be a translation of the same Valarin name (WJ/401).