Mashiach משיח
The awaited king of David's line, with whom exile ends and the world is set right.
Mashiach means «anointed»: the title of kings and high priests, and the promise of an eternal dynasty given to David by the prophet Natan underlies the whole idea. The prophets describe the messianic age as an ingathering of exiles, a rebuilt Temple, peace between nations — swords beaten into ploughshares — and knowledge filling the earth.
The Rambam states it soberly and includes it among the thirteen principles: «I await him every day». He insists the laws of nature will not change and that no miracles need be expected: the Mashiach is a king of David's line who studies Torah, gathers the people and rebuilds the Temple. And he warns against calculating dates.
History shows the cost of error: Rabbi Akiva saw Mashiach in Bar Kochba, and the revolt ended at Betar; Shabtai Tzvi swept the Jewish world and converted to Islam.