Which term refers to a person learning the plumbing trade under supervision?

The term that refers to a person learning the plumbing trade under supervision is "Apprentice." An apprentice is typically an individual who is in the early stages of their training and is engaged in a structured program that combines practical experience with theoretical education. This training under the guidance of a qualified plumber allows the apprentice to gain valuable hands-on skills and knowledge necessary to progress in the plumbing profession.

In contrast, a journeyman plumber has completed their apprenticeship and is qualified to work independently. A master plumber has advanced skills and knowledge and often oversees other plumbers, ensuring adherence to code regulations and safety standards. A maintenance man generally refers to an individual responsible for the upkeep and repair of buildings and machinery but does not specifically indicate a focus on plumbing. The distinction is important for understanding the various levels of expertise within the plumbing trade.