trierarch
noun
tri·er·arch ˈtrī(-ə)-ˌrärk 
1
: the commander of a trireme
2
: an Athenian citizen who had to fit out a trireme for the public service
Example Sentences
Recent Examples on the Web To fund their liturgy as a trierarch, a rich taxpayer spent what a skilled worker earned in 10 to 20 years of steady pay, but instead of dodging this responsibility, most embraced it. 
Thomas Martin, The Conversation, 3 Nov. 2020
Thomas Martin, The Conversation, 3 Nov. 2020 Word History
Etymology
Latin trierarchus, from Greek triērarchos, from triērēs trireme (from tri- + -ērēs — akin to Latin remus oar) + -archos -arch — more at row
First Known Use
circa 1656, in the meaning defined at sense 1