a. [ F. quartain, in fièvre 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 ]

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 ]

n. [ L. quartus the fourth. ] (Chem.) Butane, each molecule of which has four carbon atoms. [ 1913 Webster ]