NOUN (1)

1. a malarial fever that recurs every fourth day;


ADJECTIVE (1)

1. occurring every fourth day (especially the fever and weakness of malaria);
- Example: "quartan malaria"

The Collaborative International Dictionary of English v.0.48:

Quartan \Quar"tan\, a. [F. quartain, in fi[`e]vre quartaine, L.
   quartanus, fr. quartus the fourth. See Quart.]
   Of or pertaining to the fourth; occurring every fourth day,
   reckoning inclusively; as, a quartan ague, or fever.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Quartan \Quar"tan\, n.
   1. (Med.) An intermittent fever which returns every fourth
      day, reckoning inclusively, that is, one in which the
      interval between paroxysms is two days.
      [1913 Webster]

   2. A measure, the fourth part of some other measure.
      [1913 Webster]

WordNet (r) 3.0 (2006):

quartan
    adj 1: occurring every fourth day (especially the fever and
           weakness of malaria); "quartan malaria"
    n 1: a malarial fever that recurs every fourth day