That Church that is now commonly referred to as “the Catholic Church” split away from Orthodoxy about a thousands years ago.
The Orthodox Church has remained “whole” (the original meaning up to the 5th century a.d. of the term “catholic” - beginning in the 5th century was the first time that Greek word was used to mean “universal”) without the Church of Rome being a part of Her.
The original meaning of the word “catholic” is not “whole” that would be an incomplete definition.
“Catholic comes from the Greek katholikos, the combination of two words, kata (concerning), and holos (whole). According to the Oxford Dictionary of English Etymology, the word catholic comes from a Greek word meaning “regarding the whole,” or, more simply, “universal” or “general.” The word church comes from the Greek ecclesia, which means “those called out,” as in those summoned out of the world at large to form a distinct society. So the Catholic Church is made up of those called out and gathered into the universal society founded by Christ.”
or
“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.”
or
“Early Church historian J. N. D. Kelly, a Protestant, writes: “As regards ‘Catholic,’ its original meaning was ‘universal’ or ‘general.’ . . . in the latter half of the second century at latest, we find it conveying the suggestion that the Catholic is the true Church as distinct from heretical congregations (cf., e.g., Muratorian Canon). . . . What these early Fathers were envisaging was almost always the empirical, visible society; they had little or no inkling of the distinction which was later to become important between a visible and an invisible Church” (Early Christian Doctrines, 190–1).”
catholic.com/library/What_Catholic_Means.asp