Question

but what does this definition, that a boundary is an extremity of anything, mean? is it tautologous? is that the purpose, to tell us that we will use these words the same way? or is there a distinction being made here such that “extremity” explains “boundary”?

Explanation:

The text is analyzing a definition of "boundary" as "extremity of anything", questioning if it's tautological (using similar - meaning words) or if "extremity" explains "boundary" to make a distinction. It involves examining the semantic relationship between the two terms, which falls under Linguistics (a subfield of Arts) as it deals with word meanings and their relationships.

Answer:

The analysis is about the semantic relationship between "boundary" and "extremity", falling under Linguistics (Arts subfield) to examine word meanings and their connection.