Rigor: A word with two different but related meanings in medicine: 1. A chill, usually with shivering, as at the onset of high fever and chills. 2. Rigidity, as in rigor mortis, the rigidity of a body after death. The alternate spelling rigour is chiefly British. From the French, from the Latin rigor, meaning stiffness, from rigere, to be stiff.
-ine is a suffix used in chemistry to denote two kinds of substance. The first is a chemically basic and alkaloidal substance.
It's a first-declension feminine noun. The-tia, -tiae suffix is first-declension, and it creates abstract nouns. It's seen widely in Latin and is worth memorizing as such. This word amicitia is often used in the ablative of manner, that is, cum amicitiÄ, meaning with friendship or in a friendly way..