labor (n.)youdaoicibaDictYouDict[labor 词源字典]
c. 1300, "a task, a project;" later "exertion of the body; trouble, difficulty, hardship" (late 14c.), from Old French labor "labor, toil, work, exertion, task" (12c., Modern French labeur), from Latin laborem (nominative labor) "labor, toil, exertion; hardship, pain, fatigue; a work, a product of labor," of uncertain origin, perhaps originally from the notion of "tottering under a burden," and related to labere "to totter."

Meaning "body of laborers considered as a class" (usually contrasted to capitalists) is from 1839. Sense of "physical exertions of childbirth" is 1590s, earlier labour of birthe (early 15c.), a sense also found in Old French, and compare French en travail "in (childbirth) suffering" (see travail). Labor Day first marked 1882 in New York City.[labor etymology, labor origin, 英语词源]
labor (v.)youdaoicibaDictYouDict
late 14c., "perform manual or physical work; work hard; keep busy; take pains, strive, endeavor" (also "copulate"), from Old French laborer "work, toil; struggle, have difficulty," from Latin laborare, from labor (see labor (n.)). The verb in modern French, Spanish, Portuguese means "to plow;" the wider sense being taken by the equivalent of English travail. Sense of "to endure pain, suffer" is early 15c., especially in phrase labor of child. Related: Labored; laboring.