I guess it depends on the person. It seems many (most?) people use it to describe a wine that is showing nothing but structure at the moment as opposed to just not showing well. I think part of the issue here is that “closed” means different things to different people.
Oh, and aged white wines can kick ass!
But (and kidding aside here) I have never heard anyone call a white wine closed. I’m clearly drinking in the wrong circles!
I’ve had plenty of Gewurz that people described as “closed.” But I suspect that’s because it didn’t have much to give in the first place.
Berry:
My point here is less about chemistry and more about human perception. H2S does, in fact, smell like rotten eggs. At low concentrations, though, it can influence perception of fruit without being perceived as rotten egg. Luckily, it is very volatile and blows off easily, thus an improvement after some aeration. I’ve had quite a few stinkers from the Rhone and Midi that got a lot better after pouring them into and out of a pitcher a few times. Again, though, this improvement is not about oxygen ingress, it’s about blowing off volatiles.
You’re also right about esters being the fruity-smelling compounds. However, the reason esters go away over a few years is because they equilibrate with the alcohol and water in wine and actually do disappear.
Also, there is a term for whites that aren’t doing anything: austere 
Exactly!
Hi Tom - Thanks for joing the board and contributing to the dicussion. Hope you stick around!
As far as H2S being the cuase, I have to say I highly skeptical. For it it be enough to mask other flavors I think we’d smell it and like you say it blows off pretty qucik and it can take many many hours for a wine thats all-structure at the moment to start showing fruit.