Definition from Wiktionary, the free dictionary
walkup (plural walkups)
- Alternative form of walk-up.
2009 February 26, Audrey Tempelsman, “Indian Modern Redux”, New York Times:
- The apartment is in the Flowerbox Building, a new doorman condominium on East Seventh Street named after the built-in, self-watering flower boxes that stand in contrast to the street’s dingier tenement walkups.