[occamrazor]

“Reciprocal licensing” is not precise. I think ShareAlike is more descriptive (and consistent with CC licenses).

[lucasgonze]

ShareAlike is also effective.

What we know for sure is that Copyleft is never going to work.

[clearleaf]

Never heard "ShareAlike" either, and it sounds like a proprietary file sharing feature for phones or something. I just say open source and everyone has always known what I meant.

[Tomte]

It's a term from the Creative Commons family of licenses.