(1):

(n.) One who works by the job.

(2):

(n.) One who buys goods from importers, wholesalers, or manufacturers, and sells to retailers.

(3):

(n.) One who turns official or public business to private advantage; hence, one who performs low or mercenary work in office, politics, or intrigue.

(4):

(n.) A dealer in the public stocks or funds; a stockjobber.