Quartan

Part of speech: noun (n.)

1. An intermittent fever which returns every fourth day, reckoning inclusively, that is, one in which the interval between paroxysms is two days.

2. A measure, the fourth part of some other measure.

Part of speech: adjective (a.)

Of or pertaining to the fourth; occurring every fourth day, reckoning inclusively; as, a quartan ague, or fever.