What is described as an outer enclosure that provides protection without sealing qualities?

The term that best fits the description of an outer enclosure that provides protection without sealing qualities is a grave liner. A grave liner is designed to support the weight of the earth above a grave and to protect the casket from the elements, but it does not create a seal like a vault would. It allows for airflow and drainage, making it a practical option for many burial situations without entirely sealing the casket.

Other concepts, such as a cenotaph, refer to a monument or memorial to a person buried elsewhere and do not act as an enclosure for a burial. A memorial serves as a tribute or remembrance of a deceased individual but does not provide any physical protection for the casket. Unit pricing pertains to a method of pricing for funeral services or merchandise and is not relevant to the physical structures associated with burial. Thus, the definition most accurately aligns with the concept of a grave liner.