my %words = (
   'lng'        => ['lang','long','leng','loo'],
   'sentance'   => ['sentence'],
   'thxs'       => ['this','thus']
);

my @results;

for my $key (keys %words) {
  if (defined(@results)) {
    @results = &loljoin(\@results, $words{$key}); 
  } else {
    @results = map {[$_]} @{$words{$key}};
  }
}


sub loljoin {                 #pass me two references to arrays:
  my @results = @{(shift)};   #the results so far..
  my @newwords = @{(shift)};  #and the set to add to our results
  my @newresults;
  for my $word (@newwords) {
    for my $result (@results) {
      push(@newresults,[@$result, $word]);
    }
  }
  return @newresults;
}

# results are in @results as a list of lists
# eg: for my $foo { print join(" ",@$foo) . "\n" }