Solution Architecture
The design of a specific system that satisfies a specific business problem under a specific set of constraints.
Solution architecture is the level between enterprise architecture, which decides what the organisation's landscape should look like, and software design, which decides what the code should look like. Its unit of work is one solution to one problem.
The deliverable is not a diagram. It is a set of decisions — what the system is composed of, how the pieces communicate, where state lives, what happens when each piece fails, and what all of that costs — together with the reasoning that makes each decision defensible six months later when someone asks why.
A solution architect is accountable for the decisions being right for the constraints given, not for them being the best decisions in the abstract. Changing the constraints is a different job, and usually somebody else's.