A terrine can be one of several things. Its original definition refers to an oblong, earthenware pan with straight sides, used for cooking and serving food.
The word has also evolved to mean the various dishes prepared in the loaf pan, most commonly a type of country-style pâté made with finely chopped pieces of meat.
Terrines aren't limited to meat, however, and may refer to other courses like frozen desserts. Often, ingredients are layered into the pan and the loaf is served sliced, revealing a pattern.