90 Petilianus said: "If you declare that you hold the Catholic Church, the word ‘catholic' is merely the Greek equivalent for entire or whole. But it is clear that you are not in the whole, because you have gone aside into the part."
91. Augustine answered: I too indeed have attained to a very slight knowledge of the Greek language, scarcely to be called knowledge at all, yet I am not shameless in saying that I know that ὅλον means not "one," but "the whole;" and that καθ' ὅλον means "according to the whole:" whence the Catholic Church received its name, according to the saying of the Lord, "It is not for you to know the times, which the Father has put in His own power. But you shall receive power, after that the Holy Ghost has come upon you: and you shall be witnesses unto me both in Jerusalem, and in Judea, and in Samaria, and even in the whole earth." Here you have the origin of the name "Catholic." But you are so bent upon running with your eyes shut against the mountain which grew out of a small stone, according to the prophecy of Daniel, and filled the whole earth, that you actually tell us that we have gone aside into a part, and are not in the whole among those whose communion is spread throughout the whole earth. But just in the same way as, supposing you were to say that I was Petilianus, I should not be able to find any method of refuting you unless I were to laugh at you as being in jest, or mourn over you as being mad, so in the present case I see that I have no other choice but this; and since I do not believe that you are in jest, you see what alternative remains.
Source: Answer to Letters of Petilian, Bishop of Cirta (New Advent)