Where does “прямоугольный” come from?

прямоугольный (Russian) comes from Russian у́гол, from Proto-Slavic ǫgъlъ, from Proto-Balto-Slavic *ángulas, from Proto-Indo-European h₂engulos, from Proto-Indo-European h₂eng- — curve, bend.

прямоугольный (Russian): right-angled; rectangular

Definitions

  1. right-angled; rectangular

Ancestry of “прямоугольный”, step by step

прямоугольный traces back through two separate lines of ancestry.

via Russian у́гол

StepLanguageWordMeaning
1Russianу́голangle; corner
2Proto-Slavicǫgъlъcorner, angle
3Proto-Balto-Slavic*ángulas—
4Proto-Indo-Europeanh₂engulosjoint?
5Proto-Indo-Europeanh₂eng-curve, bend

via Russian прямо́й

StepLanguageWordMeaning
1Russianпрямо́йstraight, direct
2Old East Slavicпрѧмъ—
3Proto-Slavicpręmъstraight?, correct?, direct?
4Proto-Slavicprěmъstraight?, correct?, direct?
Every word from Proto-Indo-European h₂eng- →Every word from Proto-Indo-European h₂engulos →Every word from Proto-Balto-Slavic *ángulas →