AZ,
Having given a cursory read to the sources you provided, I gladly retract my comment about the sources begin fake. They are obviously real.
It seems obvious to me, however, that the meaning of words and phrases change over time. Tosfos uses the word “agunah” to clearly indicate a case where a girl cannot get married for financial reasons. Rav Shteinman uses it to indicate a girl who cannot get married for demographic reasons (assuming the age-gap theory is correct).
But those conditions are not the ones that people think of when you use the term “agunah” today. When you use that word, two things come to mind — the classic definition of a woman whose husband has disappeared or the more modern definition of a woman whose husband refuses to grant a get to his wife.
I’m not going to argue with Tosfos and Rav Shteinman — if they say that the other conditions mentioned above are technically cases of igun, then fine, they are — the semantics don’t matter to me all that much. But don’t expect people to understand what you are talking about when you use terms outside of their colloquial meanings.
The Wolf