/kwawr"tn/ , adj.
1. (of a fever, ague, etc.) characterized by paroxysms that recur every fourth day, both days of consecutive occurrence being counted.
n.
2. a quartan fever or ague.
3. quartan malaria.
[ 1250-1300; ME quartaine febris ) quartana quartan (fever), fem. of quartanus, equiv. to quart ( us ) FOURTH + -anus -AN ]