Temporary file created by Growl, an application notification program for Mac OS X; stores information used by the Growl Dictionary (GrowlDict).
Growl temp files typically are named "Growl-[long string of characters].growlRegDict;" in Growl v.6, they may show up in the Trash in a "Recovered Files" folder and can be deleted by the user; Growl v.7 appears to fix this problem.
Program(s) that open growlregdict files
Mac: Growl
Information from FileInfo.com - The File Extensions Resource.
http://www.fileinfo.com/extension/growlregdict