What is the meaning of Serk?

shirt

A shirt used as an undergarment (e.g. an undershirt or chemise)

undergarment for women, chemise

gravestone

Bremmer, Rolf H. (2009), An Introduction to Old Frisian: History, Grammar, Reader, Glossary, Amsterdam: John Benjamins Publishing Company, →ISBN, page 29

accusative/dative singular indefinite of serkr

Source: wiktionary.org