How exactly do we define a shaman?
I believe the key feature is that the shaman undergoes a type of trance. During this state he communicates with various animal spirits as well as other entities.
This is a function that the shaman performs for his community so that the people are on good terms with the spirit world.
One example of an Inuit shaman's duty is to periodically visit Sedna deep under the ocean.
She is the goddess of the sea and is responsible for providing food for the Eskimos. The sea mammals live in her hair.
However, she has no fingers and cannot comb her hair. To prevent knotting, the shaman combs her hair for her.
This keeps her contented, and it is also insurance that she will continue to provide food.
Shamans are usually depicted with a drum, and it is with the help of this drum that he enters his trance state.
Because shamans are seen as having the power to communicate with otherwordly beings, he can be seen as a type of magician.
They can act as healers and they can harm as well using magical means.
Much of what we know about shamans comes from work done with the people's of Siberia.
I believe the word shaman itself is Siberian.