Tertian

Part of speech: noun (n.)

1. 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.

Part of speech: adjective (a.)

Occurring every third day; as, a tertian fever.