Caduceus n. : The official staff or wand of Hermes or Mercury, the messenger of the gods. It was originally said to be a herald's staff of olive wood, but was afterwards fabled to have two serpents coiled about it, and two wings at the top.

Example:
How come the Caduceus is the symbol of medical profession?

Taxonomy
Caduceus symbol, Hermes, symbol, medicine, Emblem, Stuart, Tyson, Scientific Monthly, Engle, wand, snake, Origin, god, Greek, No. 6, rod of Asclepius, serpents, medical symbol.

Defination from the web:
caduceus (pronounced /kəˈdjuːsiəs, -ʃəs/, from Greek kerykeion κηρύκειον) is typically depicted as a short herald's staff entwined by two ... In later Antiquity the caduceus might have provided the basis for the astrological symbol representing the planet Mercury and in Roman ...