apprenticeship -
The condition of, or the time served by, an apprentice.
apprenticeship -
The system by which a person learning a craft or trade is instructed by a master for a set time under set conditions.
Wikipedia
Apprenticeship is a system of training a new generation of practitioners of a skill. Apprentices (or in early modern usage "prentices") or protégés build their careers from apprenticeships. Most of their training is done on the job while working for an employer who helps the apprentices learn their trade, in exchange for their continuing labour for an agreed period after they become skilled.