Domnitor (pl. Domnitori) was the official title of the ruler of Romania between 1862 and 1881. It was usually translated as prince in other languages. Derived from the Romanian word "domn" (lord or ruler) and, in turn, from the Latin "Dominus", Domnitor had been in use since the Middle Ages. Moldavian and Wallachian rulers had sometimes been referred to by the term, though their official titles had been voievod or hospodar, especially after they were officially nominated by the Sultans of the Ottoman Empire. The title acquired an officially recognized meaning only after Moldavia and Wallachia united in 1862 to form the United Romanian Principalities under Alexander John I, who had been the ruler of states since 1859. Alexander John was deposed in 1866 and succeeded by Carol I, who held the post until 1881. When Romania was proclaimed a kingdom in 1881, Carol became its first king.