Negative scope is yet another term for project exclusions. The negative scope is included in the project scope and it states the features that are explicitly excluded from the project.
This ensures 2 things:
1- That the client cannot claim that he was under the assumption that a missing feature was included in the project.
2- The team members don't have to work on features/functionalities that are usually associated with the kind of project that they are working on but are excluded from this project.