The Greeks referred to the Horai (the plural ending "ai" shows that it's Greek) in different ways, as goddesses of weather, order, and justice. Typically, there were three, the daughters of Helios (but not according to Homer), who were named Eunomia (Good Order), Eirene (Peace), and Dike (Justice) [see Themis, Dike, and Lady Justice]. In Encyclopedia of Greco-Roman Mythology, Mike Dixon-Kennedy says that the horae were originally the children of Themis and Zeus, according to Hesiod's Theogony, and may have been part of a move by the Hellenes to impose their own order on the indigenous calendar. William Smith's Dictionary of Greek and Roman Biography and Mythology says there may originally have been two horae, Thallo (Spring) and Carpo (Autumn). They were worshiped as two in Athens, with a temple to them that held an altar to Dionysus Orthus.
The set of Roman Horae was different. Ovid names the Horae as the Latin words for the four seasons: Ver (Spring), Aestas (Summer), Autumnus (Autumn), and Hiems (Winter).