What's going haywire :

foreach ($currentword, @words)
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Why's it giving unexpected results :

because you have what you'd like to be your control variable, $currentword in the parens, which denote the list foreach will loop through. This means that your control variable is really becoming the first element of the array, and $_ steps into the place you think $currentword is taking. Since $currentword is empty when the foreach starts, you (naturally?) get "" as the first element. If you'd like to test this out, change my $currentword to my $currentword="First Element!" and see what happens.

What to do:

foreach $currentword ( @words) {
    ...
    ...
    ...
}
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This restores $currentword to its rightful throne as control variable.

actually, if you're only using $currentword in this loop, I'd recommend declaring in the loop :

foreach my $currentword ( @words)
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