What would this creature's type be, anyways? Not vermin, no, but Abberation? Outsider? It would make sense if it was an outsider, but abberation works just fine.
I'm trying to figure how to advance it, do the scimatics.
I also read somewhere that they were named Xenomorphs at one point early on, but the name didn't stick (sure, it's somewhat generic, but far less generic than 'Aliens'). It might have been in the Aliens vs. Predator novel, or might have been in one of the Aliens crossover comics.
And with the original meaning of alien, it means that they have the shape of something which isn't their own race. Which is mostly the case (when they 'infect' different creatures, they pick up aspects of the creature).