While samtregar is right in his method for keeping the keys and values together, you probably don't need to go to that trouble. Why not just do something like this:

@words = sort { $word_list{$a} <=> $word_list{$b} } keys %word_list;

foreach $word (@words) {
  print "word $word = $word_list{$word}\n";
}
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@words is already a sorted list of the keys in %word_list. Of course, this assumes that nobody is doing pesky things like adding to %word_list between the time you sorted it and the time you decided to print it.