frankfurter bun(n = noun.food) hotdog bun - a long bun shaped to hold a frankfurter;
is a kind of bun, roll
is a part of hot dog, hotdog, red hot

bun, caramel bun, cinnamon bun, cross bun, frankfurter, hamburger bun, have a bun in the oven, honey bun, hot cross bun, hotdog bun, sticky bun