immersion

Universal Words noun [U] 1 ~ (in sth) the act of putting sb/sth into a liquid so that they or it are completely covered; the state of being completely covered by a liquid: Immersion in cold water resulted in rapid loss of heat. * baptism by total immersion (= putting the whole body underwater) 2 ~ (in sth) the state of being completely involved in sth: his long immersion in politics * a two-week immersion course in French (= in which the student will hear and use only French)