To baptize someone means to perform a religious ceremony that marks their entry into the Christian faith. During baptism, a minister or priest pours water over the person's head or, in some traditions, immerses them completely in water. The water symbolizes washing away the old life and beginning fresh as part of the Christian community.

Different Christian denominations baptize people at different ages and in different ways. Some churches baptize infants, with parents and godparents promising to raise the child in the faith. Other churches wait until someone is old enough to choose baptism for themselves, which might happen in their teenage years or even as adults. Some churches sprinkle water on the person's forehead, while others fully immerse them in a pool, river, or baptismal tank.

In the Bible, John the Baptist baptized people in the Jordan River, including Jesus, which is why this ritual became so important to Christians.

The word can also mean to give someone their first experience of something, especially something difficult. When a rookie firefighter faces their first major blaze, older firefighters might say they're being baptized by fire. This phrase suggests that intense first experiences can transform someone, just as baptism marks a transformation in religious life.