1 a young trainee in the armed services or police force:
an air cadet.
▪a boy or girl of 13–18 who undergoes voluntary army, navy, or air force training together with adventure training.
▪Australian Englisha trainee or novice, especially a trainee journalist.
2 formal, or archaica younger son or daughter:
a cadet of the family of the Earls of Rosse.
▪[usually as modifier]a junior branch of a family:
a cadet branch of the family.
– DERIVATIVES
cadetship/kəˈdɛtʃɪp/noun
– ORIGIN early 17th century (in cadet (sense 2 of the noun)): from French, from Gascon dialect capdet, a diminutive based on Latincaput‘head’. The notion ‘little head’ or ‘inferior head’ gave rise to that of ‘younger, junior’.