What is "oomancy"

Oomancy (sometimes ovomancy or ooscopy) refers to divination by eggs. An example would be the oracular reading (i.e., scrying) of the shapes that a separated egg white forms when dropped into hot water. This appears to be similar to methods of molten lead divination, which ascribe meaning to the shapes and forms into which hot lead solidifies.

Along with other young girls of Salem Village, Elizabeth Parris and Abigail Williams are known to have to played at reading omens by means of an egg and a mirror (or "Venus glass"): an apparently similar system of egg divination.