baptismal immersion

Greek baptisma (baptism) derives from baptizein (to immerse) — the two terms describe the same act, immersion being the physical reality of which baptism is the theological name.

Greek baptizein (to immerse) is the NT term for the immersion ritual — baptismal immersion is not a different act but the same act named literally. Tevilah (Jewish) and ghusl (Islamic) immersion are cross-traditional cognates of the same act.