Os means “mouth” in Norwegian. Back in the 11th century, a city was founded at the mouth of the Lo River; it was named Oslo by its location. Since the 14th century, Norway was under the Danish rule, so in 1624 the city was quite reasonably renamed Christiania – after the Danish King Christian IV. Only in 1905, after a period of being a part of Sweden as well, Norway became an independent kingdom. By 1924, the slow-thinking Norwegians had finally come to the conclusion that it was not appropriate for the capital to bear the name of a foreign king when they had one of their own. But kings change, and the city is still standing at the mouth of the Lo River. So, since January 1, 1925, it has been bearing the Oslo name again.
