Conciet? A deep and wide pit which cannot be measured?
Back in the day there was the "universal" Church and there were a bunch of heretics running around in contrast. the name stuck.
Where did the use of "One Holy and Apostolic" originate?
They are in the Nicene Creed, though I don't know if they originate with that council. The four "marks" by which you can tell the true Church are these. The Church is One, Holy, Catholic, and Apostolic. A Church which does not have all 4 of these could not possibly be the true Church.
SD