Offal
The (some would say aptly named) British term for edible internal organs and extremities of animals.

Osso bucco
An Italian dish of braised veal shanks with white wine, onion, carrots, celery, and tomatoes.

Osso Buco
Veal shanks braised Italian style with white wine, tomatoes, stock, olive oil, garlic and other ingredients.

Oxtail
A very flavorful cut of meat usually from beef or veal tail. Can be very tough so, often requires long, slow braising.

Oyster sauce
A dark colored, all-purpose Chinese sauce made from oysters, water, salt, soy sauce and cornstarch.