Which term describes the used space between the end of a file and the end...

Comprehensive and Detailed Explanation From Exact Extract:

File slack is the space between the logical end of a file and the physical end of the last cluster allocated to the file. This space may contain residual data from previously deleted files or fragments, making it significant in forensic investigations.

Unallocated space refers to clusters not currently assigned to any file.

Volume slack includes slack space at the volume level but is less specific.

Host protected area is a reserved part of the disk for system use, unrelated to slack space.

File slack is a recognized forensic artifact often examined for hidden data or remnants.