of third rank, importance, or value
Brit relating to higher education
denoting or relating to service industries: compare primary1, secondary1
(Tertiary) of relating to or dating from a geological period, the first geological period of the Cenozoic era, lasting from about 65 million to about 1.6 million years ago, and marked by the dominance of mammals and the evolution of modern plants
occurring in or being a third stage
Tertiary noun
[Latin tertiarius of or containing a third, from tertius third]