Tagine (say it like "ta-zheen") refers both to the food and the terra cotta
pot it is cooked in.
The bottom of a tagine is a heavy shallow dish, shaped like a deep pie plate and glazed on the top surface. The lid is a high cone and glazed only on the outside. There's a kind of ball on top that serves as a handle.
Tagines are great for braising. Lift the lid and usually they hold lamb, chicken, goat, beef seasoned with preserved lemon and aromatic with Middle Eastern spices. But you could just as well make an Italian dish like osso bucco in it.
Food simmers in the pot, the steam rises and hits the unglazed inside surface of the lid. But instead of condensing back down into the food as it would in a metal pot, the unfinished clay absorbs it, resulting in a slow and deep concentration and reduction of the juices.