Final answer:
The proximal wall is the wall of the cavity preparation located nearest the adjacent tooth. It is important for preserving the integrity and stability of the adjacent tooth.
Step-by-step explanation:
The wall of the cavity preparation located nearest the adjacent tooth is called the proximal wall. This wall is located on either the mesial or distal side of the tooth. The mesial side refers to the side of the tooth that is closer to the midline of the dental arch, while the distal side is further away from the midline. The proximal wall is important for preserving the integrity and stability of the adjacent tooth.