Medical/Scientific:
* Analysis: The process of examining something carefully.
* Synthesis: The combination of parts to form a whole.
* Diagnosis: The identification of a disease or condition.
* Prognosis: A prediction of the course of a disease.
* Neurosis: A mental or emotional disorder.
* Paralysis: Loss of movement or feeling.
* Emphysema: A lung disease.
* Apoptosis: Programmed cell death.
* Photosynthesis: The process by which plants use sunlight to make food.
* Meiosis: The process of cell division that produces gametes.
* Mitosis: The process of cell division that produces identical cells.
Other:
* Crisis: A time of great difficulty or danger.
* Emphasis: Special importance or attention given to something.
* Hypothesis: A proposed explanation for something.
* Basis: The foundation or underlying principle of something.
* Thesis: A long piece of writing on a particular subject.
* Genesis: The origin or beginning of something.
* Stasis: A state of balance or inactivity.
This is just a small sample - many more words exist with the suffix "-sis"!