The Sacrament of Baptism takes its name from its central rite; " to baptize" comes from the Greek word baptizen, which means "to plunge" or "immerse." The plunging of the catechumens into water represents being buried with Christ, when they emerge they rise up with Christ as a "new creature."
St. Paul
"Or are you unaware that we who were baptized into Christ Jesus were baptized into his death? We were indeed buried with him through baptism into death, so that, just as Christ was raised from the dead by the glory of the Father, we too might live in newness of life (Romans 6:3-4)."
St. Justin Martyr
St. Justin Martyr called the sacrament enlightenment, because those who recieve this [catechetical] 9instruction are enlightened in their understanding (CCC1216)." Jesus is the light of the world who enlightens everyone.
Jesus in John
"Amen, amen I say to you, no one can enter the kingdom of God without being born of Water and Spirit"(John 3:5). The sacrament is also known by other names. It is called the washing of regeneration and renewl by the Holy Spirit that Jesus spoke of.