use case

Short definition from Wiktionary

Noun

1. 1
   A potential scenario in which a system receives an external request (such as user input) and responds to it.
2. 2
   A usage scenario for a piece of software; often used in the plural to suggest situations where a piece of software may be useful.
3. 3
   A usage scenario for a product, such as a piece of equipment or a tool.
4. 4
   Alternative form of use case.