How do you define a "cult"?

ICSA, a cultic studies research and educational nonprofit organization, published this definition accepted by many researchers:

Cult: A group or movement exhibiting:

• great or excessive devotion or dedication to some person, idea, or thing, and
• employing unethical manipulative or coercive techniques of persuasion and control (e.g., isolation from former friends and family, debilitation, use of special methods to heighten suggestibility and subservience, powerful group pressures, information management, suspension of individuality or critical judgement, promotion of total dependency on the group and fear of leaving it),
• designed to advance the goals of the group's leaders,
• to the actual or possible detriment of members, their families, or the community.

Excerpted from Cultic Studies Journal, 3, (1986): 119-120.

If a group that you belong to has many of the following criteria to a significant degree, you have cause for concern:

• The group is led by a one or a few individuals, charismatic, determined, domineering.
• The leader(s) are self-appointed and claim to have a special mission in life. Frequently, that mission is messianic or apocalyptic. Leaders answer to no higher authority, such as an oversight board. They are sole interpreters of doctrine and policy -- which may change frequently and whimsically.
• The group centers its veneration on the leader(s) directly, rather than on God, a higher political power, science, or whatever.
• The group structure is hierarchical and authoritarian. Rarely will you find an open election in a cult.
• The group tends to be totalitarian, with elaborate rules and rituals that occupy large parts of every day. To break a rule or ignore a ritual carries the danger of expulsion from the group.
• The group usually has two or more sets of ethics: one for the leadership, another for the membership; one for outsiders, another for insiders; a relaxed set for recruiting purposes, a much more demanding set for the committed member.
• The group usually presents itself as innovative and exclusive, even elitist.
• The group has two main purposes: recruiting new members and fund-raising. It's unlikely to support or even encourage legitimate charity work, except as a front for recruitment.