job (n.)youdaoicibaDictYouDict[job 词源字典]
1550s, in phrase jobbe of worke "piece of work" (contrasted with continuous labor), of uncertain origin, perhaps a variant of gobbe "mass, lump" (c. 1400; see gob) via sense of "a cart-load." Sense of "work done for pay" first recorded 1650s. Thieves' slang sense of "theft, robbery, a planned crime" is from 1722. Printing sense is from 1795. Slang meaning "specimen, thing, person" is from 1927.
job. (1) A low mean lucrative busy affair. (2) Petty, piddling work; a piece of chance work. [Johnson's Dictionary]
On the job "hard at work" is from 1882. Job lot is from obsolete sense of "cartload, lump," which might also ultimately be from gob. Job security attested by 1954; job description by 1920; job-sharing by 1972. [job etymology, job origin, 英语词源]