Final answer:
The Arabic word used for the Medinans who helped the migrants from Mecca is 'Ansar'. They supported the Prophet Muhammad and the Muslim migrants, termed Muhajirun, in the city that became known as Medina.
Step-by-step explanation:
The Muslims who migrated from Mecca to Medina are known as Muhajirun, and the Arabic word used for the Medinans who helped these migrants is Ansar. When the Prophet Muhammad and his followers were exiled from Mecca, they found refuge in the city of Yathrib, later renamed Medina ('the city of the Prophet'). The local people of Medina who supported the Prophet and the Muhajirun by providing them with aid and a place to stay are referred to as the Ansar, which means 'helpers' or 'supporters' in Arabic. This migration, known as the Hijra, marked a crucial point in Islamic history and is commemorated as the starting point of the Islamic lunar calendar.