- a relating to symptoms (especially malarial fever) that appear every other day
- a of or relating to a tonal system based on major thirds
a tertian tonal system
- Influenza, tertian fever, leprosy were all endemic, along with tapeworm and a mysterious intestinal infestation that made its victim long to eat earth.
- On the coastal plains, three out of four cases are of the "benign tertian" variety caused by the parasite Plasmodium vivax, and only one case out of four is "malignant tertian .
- Charles Louis Alphonse Laveran (1845-1922), French military surgeon, discoverer of Plasmodium vivax, germ of tertian malaria.