A cadet is a trainee. It is frequently used to refer those training to become an officer in the military, often a person who is a junior trainee. Its meaning may vary between countries. The term is also used in civilian contexts and as a general attributive, for example in its original sense of a branch of a ruling house which is not currently in the direct line of succession.
Read more about Cadet: Etymology, Military Context, Merchant Navy, Other Usage