#!/usr/bin/perl -w
use strict;

open WORDS, "/usr/share/dict/words" or die;
my @words = <WORDS>;
chop @words;
close WORDS;

printf "Loaded %d words.\n", scalar @words;

# Favor long words
@words = sort { length $b <=> length $a } @words;
my $re = join '|', map quotemeta, @words;

while (<>)
{
  study; # ??
  1 while s/$re/[*]/io;
  print;
}