honour

c. 1200, onur, "glory, renown, fame earned," from Anglo-French honour, Old French onor, honor "honor, dignity, distinction, position; victory, triumph" (Modern French honneur), from Latin honorem (nominative honos, the form used by Cicero, but later honor) "honor, dignity, office, reputation," which is of unknown origin. In Middle English, it also could mean "splendor, beauty; excellence." Until 17c., honour and honor were equally frequent; the former now preferred in England, the latter in U.S. by influence of Noah Webster. Meaning "feminine purity, a woman's chastity" first attested late 14c. Honor roll in the scholastic sense attested by 1872.

The initial h in honest, honor, etc., is merely etymological, the sound having already disappeared when the word came into ME use. [Century Dictionary]

It was a Latinate correction that began to be made in early Old French. From c. 1300 as "action of honoring or paying respect to; act or gesture displaying reverence or esteem; state or condition inspiring respect; nobleness of character or manners; high station or rank; a mark of respect or esteem; a source of glory, a cause of good reputation." Meaning "one's personal title to high respect or esteem" is from 1540s. Bartlett ("Dictionary of Americanisms," 1848) reports honor bright! as "A protestation of honor among the vulgar."

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]