Since the distance between A and B is the same as distance between B and A, you are looking for unordered combinations of two words, so you presumably want to remove a word once is has been combined with all other words, so that you don't find the same pair again. Here is a quick simple example to make such combinations:

use strict;
use warnings;
my @array = sort {$a <=> $b} qw/ 23 45 12 4 8 7 5/;

while (my $item = shift @array) {
    print "$item $_\n" for @array;
}
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This will print all combinations of the numbers in the list:

4 5
4 7
4 8
4 12
4 23
4 45
5 7
5 8
5 12
5 23
5 45
7 8
7 12
7 23
7 45
8 12
8 23
8 45
12 23
12 45
23 45
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Just replace the print statement by the distance calculation (and the number in the original list by your words), and you're done. Just three lines of code.