amulet

n.
An object worn, especially around the neck, as a charm against evil or injury.
n.
Some object superstitiously worn as a remedy for or preservative against disease, bad luck, accidents, witchcraft, etc.
n.
An ornament, gem, or scroll, or a package containing a relic, etc., worn as a charm or preservative against evils or mischief, such as diseases and witchcraft, and generally inscribed with mystic forms or characters. [Also used figuratively.]

Wordnik from The American Heritage® Dictionary of the English Language