The word is coined by Ferraro, a famous Paladin blogger, which she refers to as the act of playing a good paladin with respect to the three trees namely Protection, Retribution, and Holy.  In simple terms, it means you’re playing those 3 specs very well.   

I feel most comfortable with playing Retribution of course because that’s the spec I leveled and raided with mostly.  But since the advent of dual-speccing, I have gotten to learn the ropes of Pally healing and have every now and then dip into playing a tank too in Naxxramas raids before (back in 3.0) and in some dungeons.  Paladining is a continuous progress though since every aspect of the tree depends on the changes made by developers in every patch or hot fix they implement, and the encounters they design.  Therefore, I cannot with much bravado claim that I am an excellent Paladin because I know I still have a lot to learn.  And learning how to play a class or a certain spec of that class takes time and a good chunk of effort I must add. 

I have intimated this previously and I will say it again here, I have not been a good ret paladin before.  Back when we were still leveling and doing heroic dungeons when we finally leveled to 70, I was a certified scrub.  I did not know what was the right spec, the combat rotation, or proper gearing.  Hence, I was at the bottom of the barrel in DPS meters and was being “outdpsed” by Weiland who was tanking.  Then the officers started to plan for Karazhan raid and it finally hit me that I need to start playing well because I would then be entering a higher level of content.