chiburashka,
Did you try the code? Before you say that isn't what you need you should see if you understand what is being presented. It is a reference and there are plenty of ways of determining what is being refered to.

Figuring out how to apply this knowledge to solve your problem is left to you unless you want to take the time to try and understand what is being presented and disclose the full details of what you want.

#!/usr/bin/perl
use strict;
use warnings;

my $h = {
    word1 => [ ('a' .. 'c') ],
    word2 => [ ('d' .. 'f') ],
};
push @{ $h->{word1} }, $h->{word2};

for my $word ( sort keys %$h ) {
    print "$word :\t";
    for my $letter ( @{ $h->{$word} } ) {
       print ref $letter eq 'ARRAY' ? @$letter : $letter;
    }
    print "\n";
}
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