A prophecy by using onions or their sprouts: Cromniomancy is a divination by the way of names, significant happenings, or missing persons written on onions, planted, and observed to see which one would sprout first.

The onion which sprouted most rapidly indicated that the person whose name had been inscribed on it was enjoying vigorous health.

Another application was that wishes would come true if a person burnt onion skins on a fire. Sometimes the onions had to be placed on the altar at Christmas before they had any divine significance.