When they throw the 'overqualified' term, what do they actually mean by it?

For 2 years now I'm unemployed and I have sent my resume to multiple recruiters that they are trying really hard to help me find a job.

Many candidate employers told them that I'm overqualified and thought at first it was a joke.

Then I went to various interviews and indeed within my 2-year unemployment span I would get rejected with the now fully-accustomed term of 'overqualified'.

A few days ago that I was rejected for yet another time I have decided to write an article, kind of a mixture of ranting and asking them in a way.

For those who are interested you can read it at https://stefanos82.github.io/posts/2017/05/28/when-you-are-overqualified-whatever-that-means.html and answer accordingly if you want.

I feel so worthless right now, but I'm so eager to learn new things.

Would you be so kind to provide me your valuable feedback? You are my only hope, cheers.