It depends quite critically on what THIS set actually is. It would make it easier to answer a question if it is accompanied by the relevant information!
Statistic
'A' is being used as the name of some set in a problem or example. 'Set' is the term for a group of numbers with some characteristic, maybe the answer to a problem, maybe just a description (like the set of even numbers).
problem
thats your problem not mine hahah
The Set a natural number between four and 20
58
flow chart
This is a description of a microprocessor.
In database technology, domain refers to the description of an attribute's allowed values. The physical description is a set of values the attribute can have, and the semantic, or logical, description is the meaning of the attribute.
The problem in The Bad Seed is that a young girl might be committing murder.
Sterile tray set-up.
This description touches most closely on the story's: