Where does “grand duke” come from?

grand duke (English) comes from English grand, from Middle English grand, from Anglo-Norman graunt, from Old French grant, from Old French -ur, from Latin -or, from Proto-Italic -ōs, from Proto-Indo-European -ōs — Creates action nouns or result nouns from verbs;...

grand duke (English): Ruler or monarch of a grand duchy; Son or...

Definitions

  1. Ruler or monarch of a grand duchy; Son or...

Ancestry of “grand duke”, step by step

grand duke traces back through two separate lines of ancestry.

via English grand

StepLanguageWordMeaning
1EnglishgrandOf a large size or extent; great; Great in size,...
2Middle Englishgrand
3Anglo-NormangrauntLate Anglo-Norman spelling of grant
4Old Frenchgrantbig, large
5Old French-ur-er, used for form agent nouns
6Latin-orused to form a third-declension masculine...
7Proto-Italic-ōsCreates masculine action nouns or result nouns...
8Proto-Indo-European-ōsCreates masculine and feminine action nouns or...
9Proto-Indo-European-oss
10Proto-Indo-European-osCreates action nouns or result nouns from verbs;...

via English duke

StepLanguageWordMeaning
1EnglishdukeThe male ruler of a duchy; The sovereign of a...
2Old Frenchducduke
3Latinduxleader, head; commander, general, captain;...
4Latindūcōto lead, guide, conduct, lead away
5Proto-Italicdoukōlead
6Proto-Indo-Europeandéwketi
7Proto-Indo-Europeandewk-to pull, to draw; to lead
Every word from Proto-Indo-European -os