Where does “rainstorm” come from?

Rainstorm combines English rain with English storm, with rain deriving from Old French resne through Proto-Germanic sturmaz, ultimately tracing to Proto-Indo-European reǵ-.

rainstorm (English): A storm characterized by substantial, heavy...

Definitions

  1. A storm characterized by substantial, heavy...

Ancestry of “rainstorm”, step by step

rainstorm traces back through two separate lines of ancestry.

via English storm

StepLanguageWordMeaning
1EnglishstormAny disturbed state of the atmosphere, especially...
2Middle EnglishstormA storm; an instance of intense wind and...
3Old Englishstormstorm
4Proto-West Germanic*sturmstorm
5Proto-Germanicsturmazstorm
6Proto-Indo-European(s)twer-to rotate, swirl, twirl, move around; to turn...

via English rain

StepLanguageWordMeaning
1EnglishrainCondensed water falling from a cloud; Any matter...
2Middle Englishreynrain water falling from a cloud
3Old Englishreġnrain
4Proto-West Germanicregnrain
5Proto-Germanicregnąrain
6Proto-Indo-EuropeanHreǵ-to flow

Words derived from “rainstorm

Every word from Proto-Indo-European (s)twer-