check_words.pl

#!/usr/bin/perl

use strict;
use warnings;
use 5.010;

my %letter;
@letter{'a' .. 'z'} = reverse 'a' .. 'z';

open my $word_fh, '<', '/usr/share/dict/words' or die $!;

while (<$word_fh>) {
  chomp;
  next if /[^a-z]/;
  if (check_word($_)) {
    say length $_, " : $_";
  }
}

sub check_word {
  my $word = shift;

  my @letters = split //, $word;

  for my $x (0 .. $#letters) {
    return if $letters[$x] ne $letter{$letters[-1 - $x]};
  }

  return 1;
}