Stair is a step, or a flight of steps, that you climb between two levels, while stare is a long, fixed look at someone or something. A simple hook: stair has an i, like a step you climb; stare has an e, like the eyes doing the looking.
The core difference
Stair refers to a step or a flight of steps; stare refers to looking at something fixedly for a long time.
- stair — a single step, or a flight of steps connecting two levels: Mind the loose stair near the top.
- stare — to look at something or someone for a long time without looking away, or the look itself: He stared out the window, lost in thought.
How to tell them apart
Stair and stare are close enough in spelling and pronunciation that they are easy to swap while typing quickly, even though their meanings have nothing in common. Stair is always about steps, whether it is one loose stair near the top of a flight or the whole staircase itself.
Stare, on the other hand, is entirely about the eyes: a long, unbroken look, as when someone stares out a window lost in thought, or gives a blank stare in response to a question. If the sentence involves climbing or steps, you want stair; if it involves looking, you want stare.
