Made of sheep's or calf's viscera minced with oatmeal and suet and onions and boiled in the animal's stomach WordNet 3.0 & Open English WordNet

Haggis is a savoury pudding containing sheep's pluck, minced with onion, oatmeal, suet, spices, and salt, mixed with stock, and cooked while traditionally encased in the animal's stomach though now an artificial casing is often used instead. Wikipedia

Scottish dish. Wikipedia Disambiguation

A traditional Scottish dish made from minced sheep offal with oatmeal and spices, etc., originally boiled in the stomach of a sheep but now often in an artificial casing, and usually served with neeps and tatties (mashed swede and potatoes) and accompanied with whisky. Wiktionary

Traditional Scottish dish. Wiktionary (translation)