A chicken sandwich is a sandwich that typically consists of boneless, skinless chicken breast or thigh served between slices of bread, on a bun, or on a roll. Variations on the "chicken sandwich" include the chicken burger, chicken on a bun, chickwich, hot chicken, or chicken salad sandwich.
In American English, a sandwich is any two pieces of bread with filling, including rolls and buns; in British English (and also some other national English varieties, such as those of Canada, Australia and New Zealand), the word sandwich is defined more narrowly, to require the pieces of bread to be sliced from a loaf, and a roll or bun with filling would not generally be called a sandwich. A bun with a cooked chicken breast as filling would generally be called a chicken sandwich in the U.S., but in British English, commonly spoken in Commonwealth countries, such a dish is not considered a sandwich, and would generally be called a chicken burger instead; most Americans would not consider such as dish to count as a burger, since Americans generally consider a burger to require a patty made from ground/minced meat.