Tertian /(?)/

Ter·tian

Tertian

a.
  1. Occurring every third day; as, a tertian fever. (Med.)

Tertian

n.
  1. A disease, especially an intermittent fever, which returns every third day, reckoning inclusively, or in which the intermission lasts one day. (Med.)
  2. A liquid measure formerly used for wine, equal to seventy imperial, or eighty-four wine, gallons, being one third of a tun.