Probably from Greek ‘ερμα (herma) meaning "cairn, pile of stones, boundary marker". Hermes was a Greek god associated with speed and good luck, who served as a messenger to Zeus and the other gods. He was also the patron of travellers, writers, athletes, merchants, thieves and orators.
This was also used as personal name, being borne for example by a 1st-century saint and martyr.