Basically, it's a term invented by Vaticanologists to mean that one might be 'popeable' - that is likely to be elected pope. Vaticanologists are like those 'constitutional historians' or 'royal biographers' the BBC wheels out every so often - like them, they range from the bonkers to the frankly useless and normally talk nonsense.
Wikipedia says that the most famous Vaticanologist was Peter Hebblethwaite - who my grandmother claimed wore a hole in her carpet playing snooker with my uncle.
'He who enters the Conclave as Pope, leaves it as a Cardinal'
Lists of papabili are mainly wishful thinking and tend to tell you more about the people who drew them up. A example is Cardinal Martini, who has died aged 85 - he was touted in 2005 as the hope for liberal catholicism. The fact that the new pope was being elected by a conclave consisting of electors appointed by a conservative pope meant nothing...
|Cardinal Martini - considered papabile in 2005|
I used to read a blog that would get over-excited when cardinals wore the cappa magna and Benedict XVI reintroduced the camauro. It would love the picture of Martini in ermine.
I sometimes think that I've over-dependent on Wikipedia, but then I find that it has pages on Benedict's dress-sense and the world's largest collection of clerical hats. Y'gotta love it!
Despite all this ecclesiastical queenery, I'm a liberal myself and would probably tend towards Martini's flavour of Catholicism...