@ignore should stay intact because you're not modifying it. There's a couple of other problems with the code though.
- You're reusing $line
- You're using $_ although it never gets initialized

I think this is what you intended to do (untested) 
$_ = qr/\Q$_\E/ for @ignore; # precompile regexes
foreach my $line (@words){
   $line =~ tr/A-Z/a-z/;  # or lc()
   foreach my $ignore (@ignore){
      $line =~ s/$ignore//g;
   }
}

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--perlplexer

In reply to Re: Nested foreach by perlplexer
in thread Nested foreach by esoteric neonate

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