Quin"tan (?), a. [L. quintanus, fr. quintus fifth, quinque five. See Five.]
Occurring as the fifth, after four others also, occurring every fifth day, reckoning inclusively; as, a quintan fever.
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n. Med.
An intermittent fever which returns every fifth day, reckoning inclusively, or in which the intermission lasts three days.
© Webster 1913.