What's YOUR definition of an 'influencer?'

In advance of the June 3 conference on PR Measurement in Washington DC, PR News Online is asking for definitions of an 'influencer' in social media.  

PR News will 'feature' the top 10 answers at the conference and on prnewsonline.com

Here's my answer:

Influencer=5 P's

• Popular:  visible, vocal, has a substantial following, reach.  In-bound links, trackbacks, subscribers, bookmarks, followers, friends, views, listens, saves, downloads, etc. 
• Polarized in tone:  neutrality does little to drive influence way or the other.  A clearly positive or negative  view will polarize readers/followers and is more likely to drive cohesion and mobilize advocates and have those advocates coalesce around a core theme, idea, or call to action.    
• Prolific / Relevant / Frequent:  raw author contribution and # of on-topic, related posts
• Prominent / Authoritative:  are they an idea starter or spreader; source or spider?  They may be prolific but are they prominent?  Are they highly inter-related, inter-connected, and centrally located in the network?  How engaged is this person’s following in a dialogue?  How much dialogue is there and what is its nature?   Here we need to reconize, though, that authority is contextual and topical.  One might be an authority on PR measurement but not on 18th century Russian literature. 
• Promoter / Advocate:  how many of the followers/commentators active contributors advocating, endorsing, advancing (or the opposite) your position?  Are they adding links, tags.  Is the nature of the language they are using inter-connective, expanded, clarifying, reinterpreting?  RTs, digs, fans, votes, buzzups, up/downloads, shares, likes, invites, favorites, embeds.  (More active than the metrics in popularity)

Of course, measuring influence (or potential to, really) is only part of a more systems, network analysis, social capital-informed approach to social media measurement.  For that, we need to consider the:

The 7 C's of Social Media Measurement

What's YOUR definition?