Deviled ham is a spreadable processed meat product made by blending cooked ham with mustard, Worcestershire sauce, cayenne pepper, paprika, or similar seasonings into a spicy, savory spread. It became a popular shelf-stable convenience food in the United States in the 19th century, and brands still vary their seasoning blends and grind, from smooth to chunky.
It's most often used as a cracker or sandwich spread, on toast or crostini, or stirred into dips, deviled eggs, macaroni and cheese, or casseroles.