Caduceus is from Greek to mean "herald's staff". The staff was carried by Hermes Trismegistus in Greco-Egyptian mythology and Hermes in Greek mythology. The same staff was also carried by Iris, the messenger of Hera.

Caduceus as the Rod of Hermes is a winged staff with two snakes wrapped around it. It was an ancient astrological symbol of commerce and is today used to symbolize the practice and profession of medicine.

As a symbol for medicine, caduceus is often used interchangeably with the Rod of Asclepius (single snake, no wings), although many people believe that the Rod of Asclepius is used strictly to symbolize the practice commerce.

More Info: en.wikipedia.org