Zealandia, while interesting in many ways, doesn't come close to meeting my definition of a continent. I wish they would stop calling it that.
So, I think the definition of what is, and what is not a continent is generally... fluid at this point.
See also: definition of a planet. How can you define what a planet is, if you keep discovering new ones, that don't quite fit the old definition? Pluto was "discovered" < 100 years ago.
I remember being taught in school that there was only three kingdoms of life!
Science! It changes. And that's a good thing.
a) It is much too small. b) It is underwater.
The fact that it was at one time above sea level is not particularly relevant in this discussion. Much of the Mojave desert used to be underwater. Does that mean it is currently a sea?
The point is that your personal opinion is badly formed. Your definition of a continent is almost completely useless, which is obvious when you just look at a map. How large is "large"? Is Greenland its own continent? How do you classify Indonesia?
The new definition at least makes sense. It updates the word's meaning to reflect a more scientifically literate understanding of continent formation.
You are right, of course, that the term is poorly defined and not very useful. It is defined mostly by convention and somewhat inconsistently. I don't believe that Greenland is generally considered to be a continent by anyone nor any of the islands in Indonesia. In my mind, even Australia is borderline, but it is generally considered to be a continent. Anyway, my point was that Zealandia is so far outside the conventional definition of a continent that it is not useful to call it that. I realize not everyone will agree with me, and I would be less annoyed if people were to refer to it as "A submerged continent" rather than "THE eighth continent."
All that said, I've spent far more words on the subject than it is worth; I really don't care as much as it probably appears. I'm really only taking issue with your assertion that my "personal opinion is badly formed."
I like your second comment a lot better. I agree that calling it a submerged continent is much better than just calling it a continent.