The way I understood the OP was print out the word which when in reverse matches any other word. Your solution does the opposite. For example instead of printing bar since 'rab' matches in arabic, it prints arabic. ymamaa was also printed since 'mamy' in reverse matches it. My point is that arabic in reverse doesn't match anything.

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

my @words = qw(mamy dady bal foo bar xrabbit ymamaa arabic);
my $list = join ' ', @words;
foreach( @words ) {
    my $rev = reverse $_;
    print "$_\n" if $list =~ /$rev/;
}
__END__
mamy
bar
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