The word "immersion" comes from the Latin word "immersio", which means "a plunging into or dipping into water". The prefix "im-" means "in" or "into", and the root word "mersio" comes from the verb "mergere", which means "to dip or immerse". The term "immersion" has been used in English since the early 17th century to refer to the act of submerging something in water or other liquid.