That follows a sinuous course, takes or has a curvilinear form, or is full of bends and turns. Of a staircase: Spiral. Chiefly in winding stairs…

having a half-pace.

Of a bent form like a dog's hind leg. Designating a stair which has no well and a bend of 180° in it, usually at a landing halfway between…

Having a newel, esp. of a specified kind. Frequently as the second element in compounds, as open-newelled, solid-newelled, etc.

Of steps: arranged in flights.

Of a staircase, ramp, roof, etc.: having a rise (rise, n. 2a) that is low; not steep, relatively flat.

(of a staircase) having no risers.