In 1616, it was granted the status of a free royal city under the name of Maros-Vásárhely by prince (fejedelem) Gábor Bethlen. Mózes Székely the only prince of Szekler origin visited the city in 1603 when he liberated Transylvania from foreign domination. In 1602, the troops of Gergely Németh put on fire the remaining houses of the town, therefore, in 1602 the reconstruction of the fortress was started on the advice of mayor Tamás Borsos, but it was actually built between 16.
In 1600–1601, as a result of the siege of Giorgio Basta, the fortress turned to ruins. In 1571, the session of the Transylvanian parliament under prince John II Sigismund Zápolya accepted the free preaching of the word of God, including by the Unitarian Church. In 1557, the Reformed Church College (i.e., Presbyterians) was established as the oldest Hungarian school of Transylvania. In 1506, the troops of Pál Tomori were beaten by the Székelys rising against the payment of an extraordinary Ox tax imposed on them on occasion of the birth of Louis II of Hungary. In 1492, wayvoda (prince) István Báthory strengthened its monastery with fortifications. In 1470 King Matthias Corvinus granted the first judicial privilege to the city, and in 1482 declared the city a royal settlement. In 1405, the King of Hungary Sigismund of Luxembourg granted the city the right to organize fairs. Since 1439 the town was the scene of the sessions of the Transylvanian parliament (diet) 36 times. In its place, the Franciscans started building a new Gothic-style church around 1332, which was completed in 1446. In place of its Fortress' Church, the Dominican church stood until the Mongol invasion, when it was destroyed. It is mentioned in the papal registry under the Latin name Novum Forum Siculorum meaning New Szekler Marketplace, and under the Hungarian name Sekulvasarhel (Székelyvásárhely) meaning Szekler Marketplace in 1349. The first known recorded documentation of the city dates to 1332. Another spelling reform in 1993 replaced the letter î with â in many words and the city's name has since been officially spelled "Târgu Mureș". After World War II, the spelling of the city's name was changed to Tîrgu Mureș, following a 1953 spelling reform that replaced the letter â with î in all words. The name Târgu Mureș became common in the interwar period. Īfter World War I, Marosvásárhely became part of Romania and was renamed Oșorheiu. Other historical Romanian names for the town besides Oșorhei were Mureș-Oșorhei and Târgul-Mureșului other historical Hungarian names in addition to Székelyvásárhely included Újszékelyvásár and Újvásár. The Romanian name for the city, Oșorhei was a phonetic derivation from Vásárhely while the German name for the town, Neumarkt am Mieresch (also shortened to Neumarkt or Marktstadt in Transylvanian Saxon, Nai Mark or Nai Muark), can be translated as New Market. In 1616, Gabriel Bethlen gave the name Marosvásárhely to the newly upgraded royal free city. Īnother written reference of the city was in the Papal registry in Latin as Novum Forum Siculorum in 1332, and later as Sekulvasarhel (modern Hungarian: Székelyvásárhely), meaning "market of the Székelys", in 1349. A second work of his, Curiesiera et Selectiera Variarum Scienetiomm Miscellanea (dated 1702) also mentions this name. He provides the year 1230 for the reference. The Jesuit priest Martin Szentiványi provides the first known written reference naming the city in his work Dissertatio Paralipomenonica Rerum Memorabilium Hungariae (written in 1699) he records the name as Asserculis by stating, in Latin, Asserculis, hoc est Szekely Vasarhely, meaning, Asserculis, here is Szekely Vasarhely. Local Hungarians often shorten Marosvásárhely to Vásárhely in speech. Târg means "market" in Romanian and vásárhely means "marketplace" in Hungarian.
The current Romanian name of the city, Târgu Mureș, is the equivalent of the Hungarian Marosvásárhely, both meaning "market on the Mureș (Maros) ". The top sign reflects the pre-1993 version Tîrgu-Mureș. Marosvásárhely is the Hungarian name and Neumarkt am Mieresch, German.