Gun bill is 'nixed' - dealt a fatal blow

Today's LNP features an article titled  "Pennsylvania law aiding NRA lawsuits nixed by high court. But what does "nixed" mean? The text of article states that the law "received a fatal blow," the first sentence of which is shown here:

"A Pennsylvania law designed to make it easier for organizations such as the National Rifle Association to challenge the firearms ordinances of local municipalities in court received a fatal blow Monday."

So, "nixed" is synonymous with "received a fatal blow" in this article about guns.

The Urban Dictionary defines it thus:

The logical conclusion is that if someone says you are nixed, it is an obvious threat, because they mean you are about to receive a fatal blow. In street parlance, you are about to be "rubbed out" or "killed."