Technical terms were still being developed when the New Testament was being written, and defined later for precision. For example The word for priest derives from the Greek presbyteros, which means elder or senior, although in the early Christian presbyteros could refer to a bishop or a priest. The English word "priest" is a derivative of the word presbyter.
The word ‘catholic’ itself is not found in the Bible. However “KAΘ OΛHC” (pronounced as ‘kath oles’) is found in the of Acts 9:31.
A
three word phrase from Acts 9:31 is “EKKΛHCIAI KAΘ OΛHC” (pronounced as
“ekklesiai kath oles”) which is Koine Greek for “church all over” or
“church universal.” Swap those words around and you get “universal
church.” This is exactly what the word Catholic means, the Universal
Church, i.e The Catholic Church. We will cover this more below.
While of course this reference isn't definitive but is does circumstantially point to the origins of the term "Catholic" for the true Church.
