The term "jobber" implies a middleman who buys goods from the wholesaler and sells it to the retailer. The principal difference between a jobber and an agent or a broker is that the latter sells goods on another person's behalf while the jobber actually buys the goods himself and then sells to the retailer.
The term "jobber" can also mean a professional wrestler who loses deliberately quite often. In the world of tennis, it refers to the player who just about manages to win matches through insipid, uninspiring performances. A musician who becomes a part of the band with the only purpose to make money or to play for a specific period of time is called a jobber. Such a person is not really interested in making music a career and he is doing the job only for a temporary period of time till an alternative comes his way.
The term "jobber" can also mean a professional wrestler who loses deliberately quite often. In the world of tennis, it refers to the player who just about manages to win matches through insipid, uninspiring performances. A musician who becomes a part of the band with the only purpose to make money or to play for a specific period of time is called a jobber. Such a person is not really interested in making music a career and he is doing the job only for a temporary period of time till an alternative comes his way.