Oh hey, are "Ducat" and "Duchy" Dominion's first pair of 100% etymological doublets?
I'm not sure on what exactly qualifies, but according to etymonline, but here are a few other quick ones I found:
* Village/Villa and Villain both share Latin villa, meaning farm or country house, but villain originally meant a farmhand.
* Dominate and Dungeon both share PIE *dem-
* Prince and Copper both share PIE *kap-
* Platinum and Plaza share PIE *plat-
So what I mean by 100% doublets is,
Ducat and
Duchy don't just come from the same
root, but actually from the same
word, with nothing else added. So
duchy is borrowed from Old French
duché, which is the reflex of Latin
ducatus; and
ducat is borrowed from Old French
ducat, which is borrowed from Italian
ducato, which is itself the reflex of
ducatus. So they both go back to the exact same word,
ducatus, just taking different routes into modern English.
Whereas, for example,
village and
villain come from
villa, yes, but they do so by adding a suffix to the root
villa, not just by letting the word take its course through time and space.
(BTW,
copper doesn't come from PIE *
kap-. Or rather,
copper 'police officer' comes from *
kap-, but the Copper in Dominion is the metal; that word comes from the placename
Cyprus.)