Where does “twothirds” come from?

Two-thirds comes from English two and English third, which derives from Middle English thridde, Old English þridda, Proto-Germanic twai, and Proto-Indo-European dwóh₁ and tréyes.

twothirds (English): Two thirds; the amount or proportion...

Definitions

  1. Two thirds; the amount or proportion...

Ancestry of “twothirds”, step by step

twothirds traces back through two separate lines of ancestry.

via English third

StepLanguageWordMeaning
1EnglishthirdThe ordinal form of the cardinal number three;...
2Middle Englishthirde—
3Old Englishþriddathird
4Proto-West Germanic*þriddjōthird
5Proto-Germanicþridjôthird
6Proto-Indo-Europeantretyós—
7Proto-Indo-Europeantr̥tyósthird
8Proto-Indo-Europeantréyesthree

via English two

StepLanguageWordMeaning
1EnglishtwoA numerical value equal to 2; this many dots;...
2Middle Englishtwotwo
3Old Englishtwātwo
4Old Englishtwēġentwo; twain
5Proto-West Germanictwai-two
6Proto-Germanictwaitwo
7Proto-Indo-Europeandwóh₁two
Every word from Proto-Indo-European tréyes →