Positive for me would be that a domain is free, so a false positive is a domain that seems to be free (no NS record) but is in fact taken (because it is registe

Positive for me would be that a domain is free, so a false positive is a domain that seems to be free (no NS record) but is in fact taken (because it is registered but nothing has been added to the DNS). But you're right, my wording wasn't precise.