Noun
The commander of a trireme.
At Athens, one who (singly, or jointly with other citizens) had to fit out a trireme for the public service.
Source: Webster's dictionaryFields (2007), p.15 The hoplites belonged to the middle social classes, so that they came immediately next to the trierarch in status aboard the ship. Source: Internet
Hanson (2006), p. 259 Trierarch The ship's captain was known as the trierarch (triērarchos). Source: Internet