Where does “roust” come from?

roust (Middle English) comes from Old English rust, from Proto-Germanic rustaz, from Proto-Indo-European rudʰso-, from Proto-Indo-European h₁rewdʰ- — red.

Ancestry of “roust”, step by step

roust traces back through two separate lines of ancestry.

via Old English rust

StepLanguageWordMeaning
1Old Englishrustred, ruddy
2Proto-Germanicrustazrust
3Proto-Indo-Europeanrudʰso-red
4Proto-Indo-Europeanh₁rewdʰ-red

via Old English rūst

StepLanguageWordMeaning
1Old Englishrūstrust
Every word from Proto-Indo-European h₁rewdʰ- →Every word from Proto-Indo-European rudʰso- →Every word from Proto-Germanic rustaz →