Meaning of "nulled" in reference to software [closed]

I've seen so many links which have this title:

ioncube php encoder nulled

What does it mean?

According to this discussion site for website admins, nulled means:

"voided, cracked, or stolen," or any other term you might want to use for "a copy not licensed by its legitimate developer."

I'd never heard the term before and, judging from what I found on Google, I think it's jargon only used by site admins who share software.

EDIT

David Schwartz (see discussion below) tells us that "null" means "remove the anti-piracy features". This term is only used for scripts and, contrary to the quote above, it does not necessarily mean that the software has been pirated.