What is the meaning of nine inch nails?

Answer 1

"Reznor said in 1994 that he coined the name "Nine Inch Nails" because it "abbreviated easily", rather than for "any literal meaning". Other rumored explanations have circulated, alleging that Reznor chose to reference Jesus' crucifixion with nine-inch spikes, or Freddy Krueger's nine-inch fingernails."

--Wikipedia

I read an interview where Trent Reznor (please say you know who he is...) talked about this, and stated basically that "Nine Inch Nails" stood the "two-week" test, it sounded cool, and he liked how it abbreviated. It isn't cos of the Jesus crucifixion thing.

And NIN music is very eclectic. Usually described as Industrial, it ranges from soft piano and touching vocals to screaming lyrics and pounding guitar riffs.

Try listening and make your own decision on that. :)