Interesting. And after looking at Mathematica (the language) more this morning, I can see the influence of Lisp and other languages. I think my definition of "lisp variant" is stricter than others' definition. I wouldn't consider Rebol, TCL or Ruby "lisp variants", even though they both derive a lot of language concepts from the lisp family. So I can't really consider Mathematica a lisp variant either.

Put it in any bucket you like, but don't ignore it. Mathematica is absolutely worth studying. If you've never used a general purpose term rewriting system before, you're missing out on some mind-altering stuff.

I'm not ignoring it, I used it years ago in grad school, it was fantastic. It just has no relevance (as a tool) to my current work or sideprojects. My question was strictly about calling it a lisp variant.

i think you're right that the "essense" is not lisp. Mathematica is more abstract than lisp, and it has lisp-like features built on top of it. that said, the analogy can be useful because things like "macros" are completely natural to the language:

    In[1]:= FullForm[a + b]
    Out[1]= Plus[a, b]

    In[2]:= a + b /. Plus -> Times
    Out[2]= a b