Where does “madadh-ruadh” come from?

madadh-ruadh (Scottish Gaelic) comes from Scottish Gaelic ruadh, from Old Irish rúad, from Proto-Celtic roudos, from Proto-Indo-European h₁rewdʰ- — red.

Ancestry of “madadh-ruadh”, step by step

madadh-ruadh traces back through two separate lines of ancestry.

via Scottish Gaelic ruadh

StepLanguageWordMeaning
1Scottish Gaelicruadhred, auburn; redheaded
2Old Irishrúadred, reddish
3Proto-Celticroudosred
4Proto-Indo-Europeanh₁rewdʰ-red

via Scottish Gaelic madadh

StepLanguageWordMeaning
1Scottish Gaelicmadadhdog, fox, wolf
2Middle Irishmataddog; cur
3Old Irishmadrad—
Every word from Proto-Indo-European h₁rewdʰ- →Every word from Proto-Celtic roudos →Every word from Old Irish rúad →