flagellant

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. One who whips, especially one who scourges oneself for religious discipline or public penance.
2. n. One who seeks sexual gratification in beating or being beaten by another person.

Century Dictionary and Cyclopedia

1. Given to flagellation, or the use of the rod; flagellating.
2. n. One who whips or scourges himself for religious discipline; specifically, in history, one of a body of religious persons who believed they could thus appease the divine wrath against their sins and the sins of the age. An association of flagellants founded in Italy about 1260 spread throughout Europe, its members marching in processions, publicly scourging their own bare bodies till the blood ran. Having by these practices given rise to great disorders, they were suppressed; but the same scenes were repeated on a larger scale in 1348 and several subsequent years, in consequence of the desolating plague called the “black death.” These flagellants claimed for their scourgings the virtue of all the sacraments, and promulgated other heresies. There have been also fraternities of flagellants authorized by the Roman Catholic Church. Some flagellants have held doctrines opposed to the Roman Catholic Church, and approximating those of Protestantism.

Wiktionary

1. n. One who practices flagellating oneself, either for penance.
2. n. A member of a religious order that preaches self-mortification as a means of absolution.

GNU Webster's 1913

1. n. (Eccl. Hist.) One of a fanatical sect which flourished in Europe in the 13th and 14th centuries, and maintained that flagellation was of equal virtue with baptism and the sacrament; -- called also disciplinant.

WordNet 3.0

1. n. a person who is whipped or whips himself for sexual gratification
2. n. a person who whips himself as a religious penance