A gabion wall is a specific type of retaining wall that is made of any number of different materials that are bound together by way of wire mesh or possibly some type of cloth. These are normally used on civil engineering projects such as roads and bridges (which explains why I am unfamiliar with the name because I am a homebuilder).
Gabion walls are typically built at an angle leaning in the direction of the higher portion of the earth. You often see these on interstate highways when there is an overpass. Often, this kind of wall is used to retain the earth around the base of the overpass.