The thoracic appendages behind the mouth parts, i.e. the appendages of somites ten to fourteen (= thoracic somites four to eight). The pereiopods consist of seven segments, these are, from proximal to distal: coxa, basis, ischium, merus, carpus, propodus, and dactylus. The pereiopods can be divided into chelipeds (those that carry a chela) and walking legs (those that do not).

Alternative forms for pereiopod : peraeopod, pereiopods, pereopod.