Even those Russians who are not supporters of Mr. Putin often deny their Ukrainian neighbors a separate identity and do not recognize Ukrainian “otherness.”

The “one people” phrase has long been an irritant for many Ukrainians, in large part because Mr. Putin has used it so often. When Mr. Putin visited Kiev in 2013 to mark the 1,025th anniversary of the conversion to Christianity of the Kievan Rus — the Medieval kingdom that gave birth to both the common culture of Russia and Ukraine — he told the assembled masses: “Wherever Ukraine may go, we still meet again sometime and somewhere. Why? Because we are one people.”

The Russian word he used, narod, was meant in Soviet and in Czarist times to represent the kinship of all the peoples and nationalities that comprised the Soviet Union and Imperial Russia. Today, the very word seems guaranteed to get under almost every patriotic Ukrainian’s skin.

Mr. Putin’s politics of history may be working well for the Kremlin within Russia, but it puts the country on ground where no one else wants to stand. Many Russians continue to use official language rooted in the Soviet period. It is difficult for them — for us — to talk without stepping into an unfortunate turn of a phrase. We still, for example, refer to World War II as the “Great Patriotic War.” But for Ukraine it was something else — something to move away from.

Russia and Ukraine have diverged in the way the identities of their respective societies work. Russians identify with the state, Ukrainians identify with a civil society. Among Ukrainians today, the best way to escape a totalitarian past is by developing a society that eclipses ethnic or state identities. This is beyond the ken of most Russians, who have trouble comprehending the idea of a society comprised of many competing elements — business, labor unions, independent political parties, courts, professional and civic groups. The Russian body politic equates society with the state. Ukraine, with its growing number of volunteer movements, nongovernment charities and independent political parties, is occupied in framing a new civic identity.

Whatever the linguistic ties between Russia and Ukraine, the words we share no longer have the same meaning. The vocabulary of the state is fading. If the two countries are to forge a new understanding, we must negotiate using the language of civility, one that can be spoken in any tongue — be it Russian, Ukrainian, English or German — with far less danger of our words being lost in translation.