n. The act of immersing, or the state of being immersed; a sinking or dipping into a fluid.n. Specifically A mode of administering baptism by dipping or plunging the whole person into water.n. Figuratively, the act of overwhelming, or the state of being deeply engaged; absorption: as, immersion in scientific studies.n. In astronomy, the disappearance of a celestial body by passing either behind another or into its shadow: opposed to emersion.n. In microscopy, the placing of a drop of liquid, such as water, between the object-glass and the object.n. In ceramics, the application of the glaze to a piece of pottery by plunging it into a vessel filled with the glaze in a liquid state.n. An antiquated term for the introduction of a solid substance into a liquid reagent in order to produce chemical change, as the calcination of tin by immersion in nitric acid.