Czecho-Slovakia or Czechoslovakia
Q: What spelling is correct?
The international treaties that formalized the creation of the new country after World War I spelled it Czecho-Slovakia, but the official spelling changed several times after that.
1919 Original hyphenation
With the Habsburgs, and effectively Austria, deposed as role-players after World War I, the existence of the new country was formalized by two treaties – between the victorious Allies (Britian, France, Italy, U.S.) and Germany in 1919 (Treaty of Versailles), and between the Allies and Hungary in 1920 (Treaty of Trianon). Their French, German, Czech, and other legal versions all hyphenated the name as "the Czecho-Slovak State."
The two Central European proclamations that emerged before the nascent government had control over the new country differed in how they spelled it. The Czech Prague "Bill on the Establishment of the Independent Czechoslovak State" of 28 October 1918, supported by four Slovaks whom its organizers managed to trace in Prague, spelled it as one word. The Slovak Martin "Declaration of the Slovak Nation" of 30 October 1918 did not refer to the new country directly, but demanded complete independence for "the Czecho-Slovak nation" having described "the Slovak nation" as its constituent part.
Tellingly, the first Provisional Constitution adopted in Prague two weeks later achieved the tough feat of not mentioning the name of the country it constituted at all.
Internally, though, Prague had already dropped the hyphen before the second international treaty was signed. The change to Czechoslovakia was indirectly formalized with the adoption of the first Constitution on 6 March 1920, which contained the unhyphenated spelling, although the hyphen continued to occur in the country's international documents for several more years. While the hyphen did not disappear completely from the Slovak press in the new country, the unhyphenated spelling prevailed. The hyphen remained more common in the Slovak-American press.
1938 Restored hyphenation
As centralist Prague's fear of Germany grew, it restored the hyphenated spelling in 1938 hoping to placate the minority in Slovakia that adhered to it, but either spelling was rendered irrelevant within months. Slovakia became a country in 1939 while the Czech-speaking territories became a province in Germany.
1945 Dropped hyphenation
When the Czech-speaking territories were rejoined with Slovakia after World War II, the hyphen was dropped once more. Its informal use was then disallowed by the communists after their takeover in 1948.
1990 Dual spelling
After the collapse of communism, the formal name of the country was changed to the Czech and Slovak Federal Republic in 1990 in order to get around the different spellings in the country's two official languages – the hyphenated spelling was restored in Slovak, the spelling mandated under communism was retained in Czech. Federal documents, whether in Slovak or Czech, used only the country's long formal name.