Catechism of the Catholic Church
830 The word "catholic" means "universal," in the sense of "according to the totality" or "in keeping with the whole." The Church is catholic in a double sense:
First, the Church is catholic because Christ is present in her. "Where there is Christ Jesus, there is the Catholic Church." 307 In her subsists the fullness of Christ's body united with its head; this implies that she receives from him "the fullness of the means of salvation" 308 which he has willed: correct and complete confession of faith, full sacramental life, and ordained ministry in apostolic succession. The Church was, in this fundamental sense, catholic on the day of Pentecost 309 and will always be so until the day of the Parousia.
831 Secondly, the Church is catholic because she has been sent out by Christ on a mission to the whole of the human race: 310
All men are called to belong to the new People of God. This People, therefore, while remaining one and only one, is to be spread throughout the whole world and to all ages in order that the design of God's will may be fulfilled: he made human nature one in the beginning and has decreed that all his children who were scattered should be finally gathered together as one.... The character of universality which adorns the People of God is a gift from the Lord himself whereby the Catholic Church ceaselessly and efficaciously seeks for the return of all humanity and all its goods, under Christ the Head in the unity of his Spirit. 311
English Translation of the Cathechism of the Catholic Church for the United States of America © 1997, United States Catholic Conference, Inc.