my @file = <DATA>;
my @array = ('file', 'this', 'dog', 'forward');
my $superterm = join '|', @array;
my @stringsfound;
my %guard;
for (@file) {
    while ($superterm ne '' and /($superterm)/gi) {
        print "Found <$1>\n"; # To watch it work
        push @stringsfound, $1;
        $guard{$1} = undef;
        $superterm = join '|', grep {!exists $guard{$_}} @array;
    }
}
print map "$_\n", @stringsfound;
__DATA__
No one could find this dog dog dog
a young boy came forward to claim this file
but his file was a mile long