quartan

(kwor’tan) [L. quart a’nus, pertaining to the fourth]. 1. Recurring every third (fourth) day. 2. A variety of intermittent fever of which the paroxysms recur on every third day. double q., a quartan fever of which the recurrences are alternately severe and relatively mild. triple q., a fever in which the paroxysms occur every day because of infection with three different groups of quartan parasites.