Tsesarevich was the title of the heir apparent or presumptive in the Russian Empire. It either preceded or replaced the given name and patronymic.
Image: Jean Louis Voille 004
Image: Constantine Pavlovich by P.E.Rockstuhl (c.1809, Hermitage)
Image: Alexander II young
Image: Nicholas Alexandrovich, Tsarevich of Russia 2
An heir apparent or simply heir is a person who is first in an order of succession and cannot be displaced from inheriting by the birth of another person. A person who is first in the current order of succession but could be displaced by the birth of a more eligible heir is known as heir presumptive.
Throngs before the Imperial Palace in Japan awaiting the appearance of the Crown Prince Hirohito for the recent proclamation of his official recognition as the heir apparent to the Japanese Imperial Throne – New York Times, 1916.