Definition of "tertian"

tertian

adjective
not comparable
1. (medicine, of a fever) Characterised by paroxysms recurring every other day (that is, every third day by inclusive reckoning).
2. (music) Pertaining to the mean-tone temperament, in which major thirds are perfectly in tune.
noun
plural tertians
1. A tertian fever.
  Quotations
  And although we feele it not, it is not to bee doubted, if a continuall ague may in the end suppresse our mind, a tertian will also (according to her measure and proportion) breed some alteration in it.
  1603, Michel de Montaigne, chapter 12, in John Florio, transl., The Essayes […], book II, London: […] Val[entine] Simmes for Edward Blount […]
  He died of the slow fever call'd the tertian, / And left his widow to her own aversion.
  1819, Lord Byron, Don Juan, Canto 1
2. The puncheon, an old wine cask, whose volume was one-third of a tun's.