*Canon law considered heresy to be the obdurate denial by a Christian of one of the fundamental tenets of Christianity. For example, among the heretical judgements of John Wyclif were the following: that the substance of the bread and wine remained in the sacrament after consecration, i.e. there was no transubstantiation at the altar; that Christ was not present in the sacrament at the altar in any form; that to someone who was truly contrite confession to a priest was neither needful nor necessary. At times the heretic might be subject to fierce punishment, such as burning at the stake. [< Gk. hairesis = choice] -
Dictionary of Medieval Terms and Phrases. Christopher Coredon with Ann Williams.