grand duke

English Thesaurus

1. a prince who rules a territory (noun.person)

hypernym	:	prince,
definition	:	a male member of a royal family other than the sovereign (especially the son of a sovereign) (noun.person)

instance hyponym	:	ivan iii, ivan iii vasilievich, ivan the great,
definition	:	grand duke of Muscovy whose victories against the Tartars laid the basis for Russian unity (1440-1505) (noun.person)