A cleaver is a large knife that varies in its shape but usually resembles a rectangular convex-shaped blade. It is largely used as a kitchen or butcher knife intended for hacking through bone. The knife's broad side can also be used for crushing in food preparation (such as garlic).
Cleavers are primarily used for cutting through thin or soft bones and sinew. With a chicken, for example, it can be used to chop through the bird's thin bones or to separate ribs.
Cleavers can also be used in preparation of hard vegetables and other foods, such as squash, where a thin slicing blade runs the risk of shattering.