Thank you, a hash is exactly what I needed, not an array.
I saw an example online, and modified it a tad:

        #!/usr/bin/perl
        while (<>) {
        @words = split(/\n+/);
                foreach $word (@words) {
                        $count{$word}++;
                }
        }
        foreach $word (sort by_count keys %count) {
                print "$word \: $count{$word}\n";
        }
        sub by_count {
                $count{$b} <=> $count{$a};
        }
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