From Middle English staire, stayre, stayer, steir, steyre, steyer, from Old English stǣġer (“stair, staircase”), from Proto-Germanic *staigriz (“stairs, scaffolding”), from Proto-Indo-European *steygʰ- (“to walk, proceed, march, climb”). Cognate with Dutch steiger (“a stair, step, wharf, pier, scaffolding”), Middle Low German steiger, steir (“scaffolding”). Related to Old English āstǣgan (“to ascend, go up, embark”), Old English stīgan (“to go, move, reach; ascend, mount, go up, spring up, rise; scale”), German Stiege (“a flight of stairs”). More at sty.
stair (plural stairs)
Usage notes 
- Stairs and stair are used to refer to a single staircase, mostly interchangeably in the UK.
Derived terms 
See also 
Forms with the definite article