[walk-up] adj (1919) 1: located above the ground floor in a building with no elevator "a ~ apartment"
2: consisting of several stories and having no elevator "a ~ tenement"
3: designed to allow pedestrians to be served without entering a building "the ~ window of a bank"
[2]walk-up n (1924): a building or apartment house of several stories that has no elevator; also: an apartment or office in such a building