It was usually translated as "prince regnant" in English and most other languages, and less often as "grand duke".

"Domnitor" is an adjective derived from the Romanian word "domn" (lord or ruler) and, in turn, from the Latin "Dominus".

The title Domn had been in use since the Middle Ages and it is also the Romanian equivalent to the Slavic Hospodar.

The title acquired an officially recognized meaning after Moldavia and Wallachia united to form the Romanian United Principalities under Alexander John I, who had become the ruler of both states since 1859.

Alexander John abdicated in 1866 and was succeeded by Carol I, who promulgated the first constitution who officially used the name Romania for the country.