1610s, "worship," also "a particular form of worship," from French culte (17c.), from Latin cultus "care, labor; cultivation, culture; worship, reverence," originally "tended, cultivated," past participle of colere "to till" (see colony). Rare after 17c.; revived mid-19c. with reference to ancient or primitive rituals. Meaning "devotion to a person or thing" is from 1829.
Cult. An organized group of people, religious or not, with whom you disagree. [Rawson]
In anthropology, an organization for the conduct of ritual, magical, or other religious observances. Many so-called primitive tribes, for example, have ancestor cults, in which dead ancestors are considered divine and activities are organized to respect their memory and invoke their aid. A cult is also a religious group held together by a dominant, often charismatic individual, or by the worship of a divinity, an idol, or some other object. (See animism, fetish, and totemism.)
Note: The term cult often suggests extreme beliefs and bizarre behavior.