(1):
(n.) Submersion in water for the purpose of Christian baptism, as, practiced by the Baptists.
(2):
(n.) The state of being overhelmed or deeply absorbed; deep engagedness.
(3):
(n.) The act of immersing, or the state of being immersed; a sinking within a fluid; a dipping; as, the immersion of Achilles in the Styx.
(4):
(n.) The dissapearance of a celestail body, by passing either behind another, as in the occultation of a star, or into its shadow, as in the eclipse of a satellite; - opposed to emersion.