Definition of "tertian" in English

adjective

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

1. A tertian fever.

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

3. A Jesuit going through tertianship.