an apartment above the ground floor in a building that has no elevator.
a building, especially an apartment house, that has no elevator.
located above the ground floor in a building that has no elevator.
accessible to pedestrians from the outside of a building: a walk-up teller's window at a bank.
is always a great word to know.
So is ort. Does it mean:
1915–20, Americanism; noun, adj. use of verb phrase walk up