1. The immersion or dipping of a believer in water symbolizing the complete renewal and change in the believer's life and testifying to one's belief in the death, burial, and resurrection of Jesus Christ as the way to salvation: To baptize someone in water was and still is a sign that the person has been accepted into the Christian faith.

The meaning of baptism is not the same for all Christian groups. For some denominations, the sacrament of baptism is performed by immersing the whole body in water, and this is done with mature people, not with babies.

2. To give a personal name to someone during the Christian ritual of baptism as some religious groups do when an infant is sprinkled with water: More generally among many church denominations, a baby is baptized during the ceremony by the sprinkling with water on the face of a baby or of an adult, and often with an baby, he or she is given a first or Christian name; in the name of the Father, the Son, and the Holy Spirit, which is called Christening.
3. Etymology: from Old French batisier (11th century), from Latin baptizare, which came from Greek baptizein, "to immerse, to dip in water"; also used figuratively; such as, "to be over one's head" (in debt, etc.), "to be soaked (in wine)"; in Greek Christian usage, "baptize"; from baptein, "to dip, to steep, to dye, to color". For sense development, baptism originally consisted of "full immersion".