Entries linking to labour
c. 1300, "a task, a project" (such as the labors of Hercules); later "exertion of the body; trouble, difficulty, hardship" (late 14c.), from Old French labor "toil, work, exertion, task; tribulation, suffering" (12c., Modern French labeur), from Latin labor "toil, exertion; hardship, pain, fatigue; a work, a product of labor," a word of uncertain origin. Some sources venture that it could be related to labere "to totter" on the notion of "tottering under a burden," but de Vaan finds this unconvincing. The native word is work.
Meaning "body of laborers considered as a class" (usually contrasted to capitalists) is from 1839; for the British political sense see labour. Sense of "physical exertions of childbirth" is attested from 1590s, short for labour of birthe (early 15c.); the sense also is found in Old French, and compare French en travail "in (childbirth) suffering" (see travail). Labor Day was first marked 1882 in New York City. The prison labor camp is attested from 1900. Labor-saving (adj.) is from 1776. Labor of love is by 1797.
word-forming element making nouns of quality, state, or condition, from Middle English -our, from Old French -our (Modern French -eur), from Latin -orem (nominative -or), a suffix added to past participle verbal stems. Also in some cases from Latin -atorem (nominative -ator).
In U.S., via Noah Webster, -or is nearly universal (but not in glamour), while in Britain -our is used in most cases (but with many exceptions: author, error, tenor, senator, ancestor, horror etc.). The -our form predominated after c. 1300, but Mencken reports that the first three folios of Shakespeare's plays used both spellings indiscriminately and with equal frequency; only in the Fourth Folio of 1685 does -our become consistent.
A partial revival of -or on the Latin model took place from 16c. (governour began to lose its -u- 16c. and it was gone by 19c.), and also among phonetic spellers in both England and America (John Wesley wrote that -or was "a fashionable impropriety" in England in 1791).
Webster criticized the habit of deleting -u- in -our words in his first speller ("A Grammatical Institute of the English Language," commonly called the Blue-Black Speller) in 1783. His own deletion of the -u- began with the revision of 1804, and was enshrined in the influential "Comprehensive Dictionary of the English Language" (1806), which also established in the U.S. -ic for British -ick and -er for -re, along with many other attempts at reformed spelling which never caught on (such as masheen for machine). His attempt to justify them on the grounds of etymology and the custom of great writers does not hold up.
Fowler notes the British drop the -u- when forming adjectives ending in -orous (humorous) and derivatives in -ation and -ize, in which cases the Latin origin is respected (such as vaporize). When the Americans began to consistently spell it one way, however, the British reflexively hardened their insistence on the other. "The American abolition of -our in such words as honour and favour has probably retarded rather than quickened English progress in the same direction." [Fowler]