/euh pos"tl it, -ayt'/ , n.
1. the dignity or office of an apostle.
2. Rom. Cath. Ch.
a. the dignity and office of the pope as head of the Apostolic See.
b. the mission of bishops in their dioceses.
c. an organization of the laity devoted to the mission of the Church.
[ 1635-45; apostolatus the office of an apostle, equiv. to LL apostol ( us ) APOSTLE + -atus -ATE 3 ]