Etymology

From Proto-Tocharian *rätre, from Proto-Indo-European *h₁rudʰros, whence Sanskrit रुधिर ‎(rudhirá), Ancient Greek ἐρυθρός ‎(eruthrós), Latin ruber, and English red from a variant form. Ultimately from the root *h₁rewdʰ-. Compare Tocharian B ratre.