Confusing. Misunderstood. Lisp is plural.
Is it fast? Yes and no - it depends.
Isn't it old? Almost the oldest. But it's not a bad thing because it never stopped to evolve. New doesn't mean powerful, by the way.
Is it object-oriented? If you need it to be, sure. Even when it's not, it is.
Is it only good for research? It's reliable and fast, but not always. It has huge libraries, but not always. It's been used in big commercial systems, too. It sure is good for research, but it can also be used commercially.
Lisp sure is hard to explain briefly. But I think I found a way to keep it to a minimum when I'll have to say something about Lisp to my future collegues.
Lisp is syntax.
The only constant between the various dialects, platforms, interpreters, compilers... is the syntax. I used to repeat that lisp has no syntax. That may be true, but if everything else is blurry and contradictory about lisp, you end up with lisp being nothing and everything. It's nothing because it's only syntax and it has no syntax. It's everything because that nothingness of a syntax is fully programmable - and people have made everything with it.
Please pardon this nothing-of-a-post. I am myself trying to understand what my new favorite programming language is. If you can light the lantern of the newb that I am, go ahead - flame at will :-)