What is the term for the process of placing remains in a crypt within a mausoleum?

The process of placing remains in a crypt within a mausoleum is known as entombment. This term specifically refers to the act of interring or sealing the remains within a above-ground structure, which is distinct from interment, where remains are generally buried in the ground. Entombment typically involves placing the deceased in a sarcophagus or a crypt that is part of a mausoleum, allowing for memorialization in an easily accessible location.

While other terms such as cremation refer to the process of reducing the body to ashes through fire, and inhumation specifies the burial of a body in the ground, entombment specifically highlights the aspect of above-ground placement within a mausoleum or similar structure. This makes it the precise term for the situation described in the question.