dura mater

This term is a specialized anatomical designation used primarily in medical, surgical, and biological contexts. It carries a highly technical register and is rarely encountered in general conversation unless discussing neurosurgery or pathology.

As a Latin loanphrase meaning tough mother, the term functions as a singular anatomical entity. In medical literature, it is treated as an uncountable noun because it refers to a specific, singular biological structure rather than a class of objects that can be counted individually.