Given the question: Question: "Apostasy in Jehovah's Witness is the definition of what?"  Context: "Formal discipline is administered by congregation elders. When a baptized member is accused of committing a serious sin—usually cases of sexual misconduct or charges of apostasy for disputing Jehovah's Witness doctrines—a judicial committee is formed to determine guilt, provide help and possibly administer discipline. Disfellowshipping, a form of shunning, is the strongest form of discipline, administered to an offender deemed unrepentant. Contact with disfellowshipped individuals is limited to direct family members living in the same home, and with congregation elders who may invite disfellowshipped persons to apply for reinstatement; formal business dealings may continue if contractually or financially obliged. Witnesses are taught that avoiding social and spiritual interaction with disfellowshipped individuals keeps the congregation free from immoral influence and that "losing precious fellowship with loved ones may help [the shunned individual] to come 'to his senses,' see the seriousness of his wrong, and take steps to return to Jehovah." The practice of shunning may also serve to deter other members from dissident behavior. Members who disassociate (formally resign) are described in Watch Tower Society literature as wicked and are also shunned. Expelled individuals may eventually be reinstated to the congregation if deemed repentant by elders in the congregation in which the disfellowshipping was enforced. Reproof is a lesser form of discipline given formally by a judicial committee to a baptized Witness who is considered repentant of serious sin; the reproved person temporarily loses conspicuous privileges of service, but suffers no restriction of social or spiritual fellowship. Marking, a curtailing of social but not spiritual fellowship, is practiced if a baptized member persists in a course of action regarded as a violation of Bible principles but not a serious sin.[note 4]"  Answer:
The answer is:
disputing Jehovah's Witness doctrines