The story
- Proto-Indo-European*h₁éǵʰ
- Proto-Indo-European*h₁éǵʰs
- Proto-Indo-European*h₁eǵʰsteros
- Proto-Italic*eksteros
- Latinexter
- Latinextrā
- Englishextra-
- Proto-Indo-European*ser-?
- Proto-Indo-European*srew-
- Proto-Indo-European*sru-dʰ-mo-s
- Proto-Hellenic*hrutʰmós
- Ancient Greekῥῠθμός (rhŭthmós)
- Ancient Greekῥυθμικός (rhuthmikós)
- Englishrhythmic
- English todayextrarhythmic
Etymology from Wiktionary, CC BY-SA 4.0.