A roar is a sound that is made from certain animals. This sound is a deep outburst from an open mouth. Roaring is made by using hyoid. A hyoid is a small bone that is not completely rigid in adults. Animals roar for a few reasons. These include when animals claim their territory (such as territorial dispute), communication with other members, and when they are angry.
Roar (vocalization) Facts for Kids. Kiddle Encyclopedia.