Words that come from Proto-Indo-European h₃erdʰ-

400 words across 53 languages descend from Proto-Indo-European h₃erdʰ- — including orthodox, Orthodox, orthodoxy, arduous, orthogonal, unorthodox, arbor, orthopedic.

See the etymology of h₃erdʰ- itself →

English (95)

Irish (57)

Esperanto (31)

French (30)

Manx (28)

Latin (24)

Italian (23)

Ancient Greek (9)

Greek (8)

Hungarian (7)

Russian (6)

Spanish (6)

Translingual (5)

Ido (5)

Romanian (5)

Old Irish (4)

Galician (3)

Yiddish (3)

Finnish (3)

German (3)

Sanskrit (2)

Old Spanish (2)

Dutch (2)

Neapolitan (2)

Proto-Indo-European (2)

Sicilian (2)

Aromanian (2)

Portuguese (2)

Scottish Gaelic (2)

Serbo-Croatian (2)

Bengali (2)

Old Armenian (2)

Proto-Italic (1)

Old Occitan (1)

Catalan (1)

Basque (1)

Venetian (1)

Dalmatian (1)

Armenian (1)

Faroese (1)

Old Leonese (1)

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Old Gujarati (1)

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Gujarati (1)

Old Marathi (1)

Marathi (1)

Macedonian (1)

Asturian (1)

Norman (1)

Norwegian Bokmål (1)

Norwegian Nynorsk (1)