(Oh my gosh I love your costume. I love horror and Pinocchio is my FAVORITE fairytale story. <3)
You're close with using a Celtic term. However, Wicca was their central religion. There were wise women and men who were healers, but they were not referred to as witches or wizards/warlocks. They were referred to as fellow Wiccans.
The original "witch" was something of the fairytale/folklore kind. She was a sort of monster and many places in Ireland are named after what forces were thought to be caused by such monsters.