a: baptism by complete submersion of the person in water
b: absorbing involvement <immersion in politics>
c: instruction based on extensive exposure to surroundings or conditions that are native or pertinent to the object of study; especially: foreign language instruction in which only the language being taught is used <learned French through immersion>
See immersion defined for English-language learners
Examples of IMMERSION
We were surprised by his complete immersion in the culture of the island.