Searching for a definition of didean

WHILE visiting Cape Cod in summer, a sign on a cottage read “Shea’s Didean”. I am unable to find the definition of “didean”. The internet gives a few places that include the word didean, but no definition.

In an article in the Irish Examiner dated 2001/10/08, the Green Party recommends forming a committee named Didean to address substandard housing. Any answers?

Chris Parker,