Herm, Greek herma, in Greek religion, sacred object of stone connected with the cult of Hermes, the fertility god. According to some scholars, Hermes’ name may be derived from the word herma (Greek: “stone,” or “rock,” such as a boundary or landmark). With the development of artistic taste and the conception of the gods as having human form, these objects tended to be replaced either by statues or by pillars that were generally square and tapering toward the bottom so as to suggest the human figure. These were usually surmounted by the bearded head of Hermes (hence the name) and had an erect phallus. They were used not only as cult objects but also for a variety of other purposes, for example, as milestones or boundary marks. They were regarded with respect, if not actually worshipped. The mutilation of the many herms dedicated in the Athenian agora, or marketplace, on the eve of the Sicilian Expedition (415 bc) led to the indictment (for the mutiliation as well as for other offenses to religion) of the expedition’s commander, Alcibiades, and ultimately to the failure of the expedition itself. Herms also occur in Roman sculpture and may have heads of the forest god Silvanus or the chief god, Jupiter Terminus. In later times, all manner of fanciful herms were used as ornaments; both single and double herms existed, and the heads were not always those of gods. A tapered rectangular stone post topped with a portrait bust is now called a herm; it is a standard element of architecture in the classical style.

Plato, Roman herm probably copied from a Greek original, 4th century bce ; in the Staatliche Museen, Berlin. Staatliche Museen zu Berlin—Preussischer Kulturbesitz