in religion, a prescribed washing of part or all of the body or of possessions, such as clothing or ceremonial objects, with the intent of purification or dedication. Water, or water with salt or some other traditional ingredient, is most commonly used, but washing with blood is not uncommon in the history of religions, and urine of the sacred cow has been used in India.

The devout follower of Shintō, for example, rinses hands and mouth with water before approaching a shrine. Monks of the Theravāda (Theravada) Buddhist tradition wash themselves in the monastery pool before meditation. The upper-caste Hindu bathes ceremonially in water before performing daily morning worship (pūjā) in the home. Jewish law requires ritual immersion of their whole bodies by women prior to marriage and after menstruation, as well as by new converts to Judaism. Washing of the hands after rising in the morning and before meals that include bread are also examples of ablution in Judaism. The Roman Catholic priest (and priests of some Orthodox churches (Eastern Orthodoxy)) celebrating the eucharistic liturgy prepares himself by ritual washing of his hands in the lavabo. Seven days after Baptism those newly baptized in Eastern Orthodox churches often go through a ceremony in which holy oil is washed from the forehead. Among some of the Brethren sects in the rural United States, ceremonial foot washing is performed on certain occasions. Muslim piety requires that the devout wash their hands, feet, and face before each of the five daily prayers; the use of sand is permitted where water is unavailable.

Like most ritual acts, ablution may carry a wide range of meanings to those who perform it. The stain of ritual uncleanness may be felt to be as real as contamination with unseen germs is for the medically minded; the act of cleansing may be only a gesture, symbolic of desired purity of soul. Or, as Carl Jung and others have suggested in studies of unconscious elements in religious symbolism, both objective and subjective aspects may be fused in the ritual act.