Why are deviled eggs so called?

Deviled foods appeared in England sometime in the 18th century. James Boswell, the biographer of Dr Samuel Johnson, compiler of the The Dictionary of the English Language, which appeared in 1755, frequently refers in his writings to eating "deviled bones."
While they sound intriguing, "deviled bones," according to a recipe from The Boston Cooking School Cook Book by 19 century cook Fannie Farmer, are nothing more than the drumsticks, thighs and wings of a chicken mixed with, among other ingredients, chili sauce, mustard and cayenne pepper.
To "devil" a food, then, is to combine it with hot or spicy seasonings such as red pepper or Tabasco sauce, the term presumably referring to the extreme heat found in hell, the devil's home.
Deviled eggs, which have long been a staple at picnics, are probably most well known deviled food. Today, however, they have been upscaled and there are now such recipes as deviled eggs with salmon and green onions.