Actually for fast lookup you would be better using a hash than an array. Something like this populates a hash from a file (substitute your file handle for DATA):

use warnings;
use strict;

my %banned;

@banned{do {local $/; split ' ', <DATA>}} = ();
print join "\n", keys %banned;

my $word = 'porn';
print "\n\n$word is on the banned list\n" if exists $banned{$word};

__DATA__
p0rn viagra phetnermine online poker
casino porn
[download]

Prints:

casino
poker
phetnermine
viagra
p0rn
porn
online

porn is on the banned list
[download]

would it be possible to include the terms I wish to restrict in a file

This is trivially done with Tie::File:

$ cat banned_words 
pr0n
hard
visit
$ perl
use Tie::File;
tie my @banned_words, 'Tie::File', 'banned_words' or die "tie: $!";
print "banned words: @banned_words\n";
untie @banned_words;
__END__
banned words: pr0n hard visit
[download]

I would just add that when looking to replace MSA stuff, your first stop should be NMS -- their wwwboard provides the banned-word-from-file functionality ... but davorg is probably better suited to speak on it.

use strict;
use warnings;

my @ban = (
    ['bleep\w*', 1],
    ['bloop\w*', 1],
    ['blark\w*', 2],
    ['blank', 1],
);

my $text = join '', <DATA>;
print check($text);

sub check {
    my ($score, $word) = 0;
    $_ = lc($_[0]);
    s/\W+/ /g;
    for $word (@ban) {
        $score += m/\b$word->[0]\b/ * $word->[1];
    }
    return $score;
}

__DATA__
Bleeping blooper! Blark you! Blank!
[download]

My advice, however (as someone who used WWWBoard for years and was constantly trying to devise a system to stop spammers) is to forget trying to solve a problem that's impossible to solve. Instead of blocking posts based on their contents, just add a visual verification system that requires people to type in a code they see in a graphic. So long as the source graphics are your own, and not from some popular system that spammers have already cracked, you should end up reasonably spam-free. Just give people a cookie after the first verification that allows them to post for a few hours without further verifications, and add a system to block bots that try to brute force your verification. This way regular users won't be inconvenienced much, and spam bots won't be able to post at all.

Of course, there may be a few real people who post obscene things, so you'll still want to replace bad words with CENSORED.

We tend to forget, but spamming has become a high-tech area. Have a look at The spammers Compendium and despair.

You would be much better to go for a tool like POPFile or Mail::SpamAssassin to classify your messages before they get allowed on the board.

Hi again, Many thanks guys - I'l have a look at that & see what I can work out. The site this board runs on is non-profit & I want to try & make it as simple for people to post as possible, while still be relatively spam-free. The format of WWWBoard is exactly what I'd like to retain, but the security of the modified 'Mr Fong Device' version has gotten to an unmanageable point now. I might try the NMS version if this other board doesn't work out or if I just can't figure out how to implement what people have suggested above.