the first floor
From Longman Dictionary of Contemporary Englishthe first floorthe first floorBritish EnglishTBBDHH the floor of a building just above the one at the bottom level → ground floor a flat on the first floor → first floorthe first floorthe first floorAmerican EnglishTBBDHH the floor of a building at the bottom level Fire broke out on the first floor of the apartment building. → first floor