tertian

Characterised by paroxysms recurring every other day (that is, every third day by inclusive reckoning).

Pertaining to the mean-tone temperament, in which major thirds are perfectly in tune.

A tertian fever.

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.

He died of the slow fever call'd the tertian, / And left his widow to her own aversion.

A cask of a certain size; its volume used as a measure of capacity (one-third of a tun's).

A Jesuit going through tertianship.