Stair
STAIR, noun
1. A step; a stone or a frame of boards or planks by which a person rises one step. A stair to make the ascent easy, should not exceed six or seven inches in elevation. When the riser is eight, nine or ten inches in breadth, the ascent by stairs is laborious.
2. Stairs, in the plural, a series of steps by which persons ascend to a higher room in a building. [Stair, in this sense, is Not in use.]
Flight of stairs, may signify the stairs which make the whole ascent of a story; or in winding stairs, the phrase may signify the stairs from the floor to a turn, or from one turn to another.