2 Answers

 HERESEY, as far as I can find.

In ancient Greek, the verb hairein, meaning "to take", gave rise to the adjective hairetos "able to choose" and the noun hairesis "the act of choosing".
In time the noun developed the extended senses of a "a choice", "a course of action", "a school of thought", and "a philosophical or religious sect". Stoicism was considered a hairesis
Within Judaism, a heresy (our Modern English equivalent and derivative of hairesis) was a religious faction, party, or sect; such as, the Pharisees or Sadducees.
Applied to such groups, hairesis was used in a neutral, nonpejorative manner.
In fact, when this Greek noun is used in the New Testament (Bible), it is usually translated as sect.
By the end of the second century, haeresis (the Latin equivalent) was being applied to an organized body holding a false or sacrilegious doctrine.
From this use, it took on the sense of "a body of doctrine substantially differing in some aspect from the doctrine taught by the Church".
The Catholic Church used the Latin haeresis (from the Greek hairesis) for "heresy" and haereticus (from the Late Greek hairetikos, a derivative of hairetos "able to choose") for "heretic".
These two words were taken into early French as heresie/eresie and heritique/eritique and then into English in the thirteenth and fourteenth centuries, respectively, as heresy an heretic.
Their religious senses passed into English as well.
In Chaucer's time, c. 1385, the noun began to take on a nonecclesiastical use, being applied to any dissenting opinion, belief, or doctrine in any field.
At about the same time we also find this noun being used for "a school of thought, a sect", echoing the ancient Greek use of hairesis.
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haeresis