tertiary (tûrˈshēârē) [key], in the Roman Catholic Church, member of a third order. The third orders are chiefly supplements of the friars—Franciscans (the most numerous), Dominicans, and Carmelites. They have rules reflecting the spirit of the corresponding order but adapted to life in the world; hence, the offices to be read are short and the fasts are mild. The promises made on joining are not vows; their purpose is the sanctification of the members. Secular members of third orders (i.e., those who live in the world) may be priests or laymen; there are also tertiaries who live in communities, the regular tertiaries. The name tertiary recalls their origin among the Franciscans, for St. Francis founded his order for laymen only after he had instituted his order for men (the friars) and after St. Clare had founded the nuns (second order, the Poor Clares). See monasticism.