n. A galley with three banks of oars, one above the other, used mainly as a warship.
the GNU version of the Collaborative International Dictionary of English
n. An ancient galley or vessel with tree banks, or tiers, of oars.
The Century Dictionary and Cyclopedia
n. A vessel with three benches, ranks, or tiers of oars on a side: a type of ancient Greek war-ship of great efficiency, copied by the Romans and other peoples.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. ancient Greek or Roman galley or warship having three tiers of oars on each side
Word Usage
"In fact, the name trireme was used loosely for all ships of war whether they had two banks of oars or three."