Which is the best example of domain-specific

The term "domain-specific" refers to language or vocabulary that is specific to a particular field or discipline. Among the options you provided, "Shape" is the best example of a domain-specific term, particularly in fields like mathematics, geometry, and design.

- **Equilateral** could also be considered domain-specific as it relates to geometry (specifically triangles), but it is more of a specific descriptor than a general term.
- **Numerous** is a general term used in various contexts and is not domain-specific.
- **Close** is also a general term that can apply to various contexts.

Therefore, while all of these words have particular contexts where they may be used, "Shape" stands out as the most broadly applicable in various domains specifically related to structure and form.