Huge Bias Warning: I created the NeoLethal tag on PaleoHacks on June 8th in my question http://paleohacks.com/questions/5835/cringeworthy-foods-adapting-to-new-drives and I might be the originator of this use of this pre-existing word.
So, I'll at least assume that I knew what I was attempting to do when I was making something new-ish.
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I came up with the word neolethal, and tried to define it as 'foods that are neolithic and harmful'.
Yes, it is a play on words {and I do love such play}, but *I was trying to brainstorm up a word that succinctly said how I was against the idea that "If it is Neolithic, it MUST be bad for you."*
Big tip of the hat to Kurt G. Harris MD of http://www.paleonu.com/ for bringing this idea solidly home to me.
After I had tried my best to make a neologism, I did a google search to see if it was used anywhere else, and the closest I could come up with was from doi: 10.1101/gad.9.22.2736 Genes & Development 1995. where it was used as a contraction of Neonatal Lethality.
That was really not the same idea as I was trying to express, but I went forward with it anyway.
-=- Stops the rambling train of thought -=-
This answer may have been way too long, SO I'll just focus and finish by saying that if a new word helps communicate a thought better and accurately, then it is not that silly.
I was making up a new word in the attempt to make my communication better, and make it easier to spread the Paleo/Primal/PāNu meme around.
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Please tell me if you get any use or Paleo-converts out of it.