Thanks for this!

I was unfortunate enough to randomly get a non-word from my /usr/share/dict/words file:

fldxt
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I added a grep to only allow words with a vowel (or "y"):

    @dict{ map uc, grep /[aeiouy]/, map /^([a-z]{5})$/, <$FH> } = ();
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I found this out by adding an option to print the current word at the end:

print "\n    Answer = $curr_word\n" if @ARGV;
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