The term BIREME is a type of GALLEY ship used by the ancient Greeks and Romans. It was powered by OARS, with two TIERS of oarsmen, and was propelled by up to three OARS per side. The OARS were arranged in a staggered pattern, with the OARS on the lower TIER being longer than those on the upper TIER. This allowed for greater speed and maneuverability. The term BIREME is derived from the Greek words 'bireme' and 'oared', which refer to the two TIERS of oarsmen. The term GALLEY refers to the type of ship, while OAR, OARS, OARED, and TIER/TIERS refer to the propulsion system.