A member of pack (or anyone who is a part of a community) for a VERY long time.
Usually used around the scene as to describe somebody who has been on the scene for a longer time, such as 10 years or so.
It is worth mentioning that since the scene does not have any official leadership these greeymuzzles do not actually hold any kind of authority. In my research I have often come to problems with some of them deciding for themselves what is 'best' for others and preffering to use words of their own making as opposed to words that have actually been in use before that they have neglected to fully understand.
Greymuzzles surely have a lot of knowledge and experience regarding what has gone on and goes on on the sceene, however keeping and open mind and not believe everything you hear them say is a good way to get to the knowledge you seek intact.