Definition of "quartan" []

• Occurring every fourth day, counting inclusively, or every 72 hours. Used of a fever. (adjective)
• A malarial fever recurring every 72 hours. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "He admitted to having been laid low by a quartan ague but insisted it was nothing to worry about."
• "In contrast, the incubation period for quartan malaria, caused by Plasmodium malariae, can be as long as thirty or forty days, with fever coming every fourth day."
• "Antonio de Ciudad Real happily notes the day, in Tratado curioso, when he realized that he was finally free from quartan fever (cuartanas), which had plagued him for more than three years. 64 Intermittent fevers like these were probably malarial, and these two cases could very well have originated in Spain, as their carriers had only recently arrived from the Peninsula."