The Greek roots of the term "Catholic" mean "according to (kata-) the whole (holos)," or more colloquially, "universal." At the beginning of the second century, we find in the letters of Ignatius the first surviving use of the term "Catholic" in reference to the Church. At that time, or shortly thereafter, it was used to refer to a single, visible communion, separate from others.
People often ask, "How should I begin to train myself to defend my faith? How do I prepare for the inevitable knock on the door? I don’t want to have to stand there open-mouthed." The best place to start your homework is the Bible. Almost every American home has one.
"Between heresy and schism there is this difference, that heresy perverts dogma, while schism, by rebellion against the bishop, separates from the Church. Nevertheless there is no schism which does not trump up a heresy to justify its departure from the Church."
~ St. Jerome, (In Ep. ad Tit., iii, 10), remarking on how practically and historically, heresy and schism nearly always go hand in hand.