The best example of a domain-specific language (DSL) from the options provided would be "shape." This is because "shape" can refer to a category that can be defined and manipulated within specific contexts (such as graphics programming or mathematical modeling), which aligns with the characteristics of a DSL.
The other options, "close," "numerous," and "equilateral," are more general terms that do not represent a specific language or domain of use in the same way.