hydromancy

If you've ever encountered a sorceress or a wizard peering into a "scrying bowl" as part of a movie or a book, you've witnessed a (fictionalized) version of "hydromancy." The word has been used since at least the 14th century to describe the use of water in divination - examples include predicting the future by the motion of the tides or contacting spirits using still water. "Hydromancy" is believed to derive ultimately from the Greek words for "water" ("hydōr") and "divination" ("manteia"); it came to English via Latin hydromantia. The ancient Greeks who relied on hydromancy also gave us the names for related forms of divination, such as "necromancy" (using the dead), "pyromancy" (with fire), and even "rhabdomancy," a fancy and now rare word for "divination with wands or rods."