Stair

1. (n.) One step of a series for ascending or descending to a different level; -- commonly applied to those within a building.

2. (n.) A series of steps, as for passing from one story of a house to another; -- commonly used in the plural; but originally used in the singular only.

Thesaurus Entries

amount, caliber, compass, cut, degree, doorstep, extent, footrest, footstep, grade, height, interval, leap, level, mark, measure, notch, nuance, pas, peg, period, pitch, plane, plateau, point, proportion, range, ratio, reach, remove, rest, riser, round, rundle, rung, scale, scope, shade, shadow, space, spoke, standard, stave, step, step stool, stepping-stone, stint, string, tread