OSIS or variant may refer to: The suffix -osis is used for forming a number of medical terms.
The suffix itself signifies only a general functional disorder, but the constructed words are more specific.
It is often used to denote a biological process (i.e. Apoptosis, Phagocytosis, Necrosis...) Osis (feminine: Ose), is a Latvian language surname meaning "ash" (tree; Fraxinus excelsior)