In planetary geology, scopulus (pl. scopuli) is the term used to describe a lobate or irregular escarpment.[1] The word is from the Latin meaning a crag, cliff, or a rock at sea.[2] The word is derived from the Greek σκόπελος, which means prominatory, peak, or headland. The word can also mean a look-out place as indicated by its root σκόπε- (scope)--to view or look.[3] In the early 1970s, the International Astronomical Union (IAU) adopted scopulus as one of a number of official descriptor terms for topographic features on Mars and other planets and satellites.[4] One justification for using neutral Latin or Greek descriptors was that it allowed features to be named and described before their geology or geomorphology could be determined.[5] Currently, the IAU recognizes 54 descriptor terms. (See Planetary nomenclature.) Thirteen features with the descriptor term scopulus are present on Mars.