tertiaireadjectivecommon nouncommon nounproper nounEtymologyexpand(1786) from Latin tertiarius. The medical sense appears in the mid-19th century. The economic sense appears in 1947.Definition1. One of the members of a third order affiliated with a religious congregation.religionexpandUn tertiaire franciscain, dominicain.PluraltertiairesSee alsoTertiaire (pn.) tertiaires (adj.)