According to the Scientologists, "Scientology" means "knowing how to know". However, the founder, L Ron Hubbard, a science fiction writer in the 1950's, never mentioned the word in his writings, as far as I know. I'm not sure when it was first used.
As for it being based on science...their higher power is an intergalactic overlord named Xenu, and they believe we're all giant clams - yes, clams - that will be freed of suffering, poverty, disease, post partum depression, homosexuality, autism, etc, if we cast out the Thetans (evil aliens) who possessed mankind ages ago after an interstellar battle. I believe they crashed into a volcano or something and were dispersed, if I'm remembering correctly.