1)one who either does not have a brain, or one who simply chooses not to use their brain. moreso, in particular, one who's neck tapers inward toward their cranial mass. i.e. one who's neck is much larger than their head, common among jockstraps or those that fail to practice common sense.
that dude is such a neckhead. i wish he would use his head once in a while.
by john moritz August 24, 2003
a person that really believes what they say is truly profound
I heard a neckhead say, "You know someday something is going to happen".
by J.F.G.N.F. October 04, 2007