Dictionary.net

The sacrament in which immersion or sprinkling with water symbolizes the washing away of sin, and which admits to membership in the Christian church; the act of sprinkling or immersing as a sacrament, or of being sprinkled or immersed; any experience by which one is cleansed spiritually, or any sanctifying ordeal; as, the adventurer here suffered his baptism of fire.

Immersion in or sprinkling with water as a religious ceremony.

BAPTISMAL.

Use of water, as a sacramental rite.

n. [Greek] Act of baptizing ; the application of water to a person, as a religious ceremony, by which he is initiated into the visible church of Christ.

Baptism is given by water, and that prescript form of words which the church of Christ doth use; baptism is often taken in Scripture for sufferings.