Definition: A term that defines the standard unit of time that one has been a WikiMember, WikiLurker, or WikiCitizen. Thus, in context, one would say that one has been a WikiCitizen for 11 WikiYears.
Sort of like "doggy-years"; an off-the-cuff measurement of WikiMembership.
To find out what real amount of time that a WikiYear is equal to, I think that we would consider what the average turn-over is for WikiZens. We would then assign this turn-over rate (for example: 3 months) as being the definition of a WikiYear. (If figuring out this turn-over rate isn't intuitive, then the community could agree on a period of time.)
Then
Would there then be cause to have such labels as WikiAncients or WikiMethusalehs? Just kidding. Seriously though, I just think that the concept would add a bit of good-natured fun.
WikiMaster, though, would still remain an accolade earned through practicing the WikiWay, instead of just being the oldest WikiMember on the block.
Also See: DoWikisHaveFiniteLifetime