In early modern England, nightmares were associated with witchcraft and the Devil, and women who were visited by these demonic creatures were said to be at risk of transforming into witches themselves. Merlin, the sorcerer of Arthurian legend, was said to have been the child of an incubus, among other historical and folkloric figures.
The two distinct meanings of the word “mare” are not always easily separated. An early definition of the word “nightmare” from the 14th century refers to an evil spirit “afflicting men (or horses) in their sleep.” The French word for nightmare, “cauchemar,” features the Old French “cauche,” which derives from the Latin “calco,” meaning “to trample.”
Over time, the word “nightmare” stopped referring to the supernatural creature believed to cause bad dreams and came to refer to the dreams themselves. Since the early 1900s, the word has not only referred to bad dreams, but also to waking life situations that people wish were bad dreams, such as accidents or misfortunes.
