trireme (n.)

word-forming element meaning "three, having three, once every three," from Latin tres (neuter tria) or Greek treis, trias "three" (see three).

*erə-, Proto-Indo-European root meaning "to row." It forms all or part of: row (v.) "propel with oars;" rudder; Russia; Russian; trireme.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit aritrah "oar;" Greek eressein "to row," eretmon "oar," trieres "trireme;" Latin remus "oar;" Lithuanian iriu, irti "to row," irklas "oar;" Old Irish rome "oar," Old English roðor "rudder," rowan "go by water, row."