remainernoun [ C ]
also Remainer uk/rɪˈmeɪn.ər//rɪˈmeɪn.ɚ/UKa person who voted for the United Kingdom to remain in the European Union in the 2016 referendum (= a vote in which all the people in a country are asked to decide an important political or social question ):
She said that Brexit would happen and remainers would be forced to accept it.