Where does “nguyên âm đôi” come from?

nguyên âm đôi (Vietnamese) comes from Vietnamese nguyên âm, from Chinese 元 — monetary unit, "especially" RMB; yuan.

nguyên âm đôi (Vietnamese): diphthong

Definitions

  1. diphthong

Ancestry of “nguyên âm đôi”, step by step

nguyên âm đôi traces back through two separate lines of ancestry.

via Vietnamese nguyên âm

StepLanguageWordMeaning
1Vietnamesenguyên âmvowel
2Chinese元monetary unit, "especially" RMB; yuan

via Vietnamese đôi

StepLanguageWordMeaning
1Vietnameseđôidouble
2Middle Chinese對—
Every word from Chinese 元 →Every word from Vietnamese nguyên âm →