Why are deviled eggs named or called (deviled eggs)? How did the name come about?

The term "deviled" dates back to the 18th century, referring to the use of particularly hot spices in cooking. Contemporary versions of deviled eggs may include a wide range of seasonings and added foods, such as garlic, horseradish, wasabi, cheese, chutney, capers, salsa, hot sauce, mushrooms, spinach, sour cream, caviar, smoked salmon, or other seafood. Thus contemporary deviled eggs are not always particularly spicy.

Around 1868, Underwood and sons began experimenting with a new product created from ground ham blended with hot seasonings. They introduced a line of seasoned meat products including chicken, turkey, tongue, lobster and ham. They dubbed the seasoning process “deviling,” and the Underwood red devil was born. It holds U.S. Patent Office trademark No. 82, granted in 1870, the oldest existing food trademark still in use in the United States.[1] While the Underwood devil is a trademark, the term "deviled" has evolved to refer to a number of foods (such as eggs) pureed with hot spices, particularly Dijon mustard.

The concept began in Ancient Rome. They were the anchesters of the Deviled eggs when they domesticated chickens. Although deviled eggs they were made as early as the 13th century in Andalusia, they got their name' deviled' in the 18th Century.

–Apicius: Cooking and Dining in Imperial Rome, edited and translated by Joseph Dommers Vehling [Dover:New York] 1977 (p. 180)

The term "deviled" was used for fiery hot spicy foods in the 18th century.