Baptisma is the technical NT term for the rite of baptism — the immersion in or application of water as a sign of cleansing, initiation, and identification. Appearing about 19 times, it is distinguished from baptismos (a ritual washing) as the specifically Christian/Johannine sacramental act. Derived from baptizō (to immerse, to dip), it is the noun designating the event or institution of baptism.
Baptisma is theologically rich in the NT. John's baptism (baptisma metanoias — baptism of repentance) pointed forward to Jesus. Jesus' own baptism inaugurated His public ministry and identity as the beloved Son. Christian baptism (Romans 6:3–4) is participation in Christ's death and resurrection — an enacted declaration that the old self has died and a new creation has risen. It is the initiatory rite of the new covenant community (Acts 2:38). Paul boldly says there is "one baptism" (Ephesians 4:5) — pointing to the unity of the body of Christ.