Ter″tian, n. [L. tertiana (sc. febris): cf. OF. tertiane.] 1. (Med.) A disease, especially an intermittent fever, which returns every third day, reckoning inclusively, or in which the intermission lasts one day.
2. A liquid measure formerly used for wine, equal to seventy imperial, or eighty-four wine, gallons, being one third of a tun.