A son of a tsar, a prince in Russia or Bulgaria(noun)
The firstborn son of a tsar(noun)
The crown prince of Russia or Bulgaria(noun)
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Use "tsarevich" in a sentence
"Olga was soon joined by her sisters Tatiana (1897), Maria (1899), Anastasia (1901), and, finally, by her brother, the long-awaited tsarevich, Alexis (1904)."
"You like, you frog from over the sea, to croak at the Russian tsarevich; but we -- we are orthodox."
"Let him curse to his heart's content; the tsarevich has nothing to do with the Otrepiev."