czarevitch
noun
czar·e·vitch ˈzär-ə-ˌvich 
ˈ(t)sär-
ˈ(t)sär- variants or less commonly tsarevitch or tzarevitch
: an heir apparent of a Russian czar
Word History
Etymology
Russian tsarevich, from tsar' + -evich, patronymic suffix
First Known Use
1710, in the meaning defined above