I'd get another dictionary, and then study the etymology of the word.
It is first used in Titus 3:10, long before the RCC came into existance, so any definition attaching itself to the RCC is proven wrong.
Here is Webster's definition, which is more accurate:
The word heretic is now commonly applied to one who holds some fundamental error of doctrine, a person who holds and teaches opinions repugnant to the established faith, or that which is made the standard of orthodoxy. Webster. The Greek word here used αἱρετικὸς hairetikos occurs nowhere else in the New Testament.
The only issue left to decide, is whether or not the RCC is fundamental or otherwise orthodox. That has already been decided. Blessings.
Merriam Websters 11th edition, C/R 2004 and your statement that the RCC is fundamental or otherwise orthodox has been decided......by whom?????and what were their credentials??? I'm sorry, but when you are a member of an organization that God Himself promised would never be in error...you are on pretty good ground against those who would challenge your opinions. I'm there, you're not.