It actually works. I created a dictionary of 50000+ words sorted by popularity. The problem was that I ran your example but I did not have "concatenated" in there.
Thanks for your explanation. I will spend some time to understand this part 
print for grep defined(), $s =~ /^$re2$/;

[download]
in details. Looks like genius. In terms of both, Perl flexibility and your implementation. Actually it needs 
print "$_\n" for grep defined(), $s =~ /^$re2$/;

[download]
to print line-wise.

I'm curious as hell about the source of the data and the purpose of the exercise?

The dictionary is the side affect of phrases I retrieved from crawling for my applications. The purpose of the exercise is the following. I created a keyword generator which is a web application. From the logs I found that some people merge words in a seed phrase and my resulted keywords filter fails to establish similarity in these cases. So I need to split. But usually it is only a two reasonable words split so that looks like your algorithm with my dictionary works well.

I can send you a link to the tool, but I am not sure it's a right way to do it through the forum.

In reply to Re^4: Splitting compound (concatenated) words ) by vit
in thread Splitting compound (concatenated) words ) by vit

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