Where does “understair” come from?

understair (English) comes from English under, from Middle English under, from Old English under, from Proto-Germanic under, from Proto-Indo-European h₁entér, from Proto-Indo-European h₁en — in; in, inside.

understair (English): Beneath a flight of stairs; Of or pertaining to...

Definitions

  1. Beneath a flight of stairs; Of or pertaining to...

Ancestry of “understair”, step by step

understair traces back through two separate lines of ancestry.

via English under

StepLanguageWordMeaning
1EnglishunderIn or at a lower level than; As a subject of;...
2Middle Englishunderunder
3Old Englishunderunder, beneath
4Proto-Germanicunderamong, between; under, beneath; under
5Proto-Indo-Europeanh₁entérbetween
6Proto-Indo-Europeanh₁enin; in, inside

via English stair

StepLanguageWordMeaning
1EnglishstairA single step in a staircase; A series of steps;...
2Middle Englishsteirestaircase, stairs; stair, step; ladder
3Old Englishstǣġerstair, staircase
4Proto-Germanicstaigrizscaffold, platform; stairs
5Proto-Indo-Europeansteyǵʰ-to go
Every word from Proto-Indo-European h₁en →Every word from Proto-Indo-European h₁entér →Every word from Proto-Germanic under →