TER'TIAN,adjective [Latin tertianus, from tertius, third.] Occurring every other day; as a tertian fever. TER'TIAN, noun A disease or fever whose paroxysms return every other day; an intermittent occurring after intervals of about forty eight hours. 1. A measure of 84 gallons, the third part of a tun.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI