Online Etymology Dictionary. Old English read "red," from Proto-Germanic *rauthaz (cognates: Old Norse rauðr, Danish rød, Old Saxon rod, Old Frisian rad, Middle Dutch root, Dutch rood, German rot, Gothic rauþs).
As a noun from mid-13c. The Germanic words are from PIE root *reudh- "red, ruddy" (cognates: Latin ruber, also dialectal rufus "light red," mostly of hair; Greek erythros; Sanskrit rudhira-; Avestan raoidita-; Old Church Slavonic rudru, Polish rumiany, Russian rumjanyj "flushed, red," of complexions, etc.; Lithuanian raudas; Old Irish ruad, Welsh rhudd, Breton ruz "red").
Red.