-or 1
a suffix occurring in loanwords from Latin, directly or through Anglo-French, usually denoting a condition or property of things or persons, sometimes corresponding to qualitative adjectives ending in -id 4 ( ardor; honor; horror; liquor; pallor; squalor; torpor; tremor ); a few other words that originally ended in different suffixes have been assimilated to this group ( behavior; demeanor; glamour ).
[ -our -or-, s. of -or, earlier -os ]
Usage . While the -or spelling of the suffix -or 1 is characteristic of American English, there are occasional exceptions, as in advertising copy, where spellings such as colour and favour seek to suggest the allure and exclusiveness of a product. The spelling glamour is somewhat more common than glamor - not actually an instance of -or 1 ,but conformed to it orthographically in the course of the word's history.
In British English -our is still the spelling in most widespread use, -or being commonly retained when certain suffixes are added, as in color ation, honor ary, honor ific, labor ious, odor iferous. The English of the Southern Hemisphere (Australia, New Zealand, South Africa) tends to mirror British practice, whereas Canadian English shares with the U.S. a preference for -or but with -our spellings as freely used variants.
The suffix -or 2 is now spelled -or in all forms of English, with the exception of the word savior, often spelled saviour in the U.S. as well as in Britain, esp. with reference to Jesus.
-or 2
a suffix forming animate or inanimate agent nouns, occurring originally in loanwords from Anglo-French ( debtor; lessor; tailor; traitor ); it now functions in English as an orthographic variant of -er 1 , usually joined to bases of Latin origin, in imitation of borrowed Latin words containing the suffix -tor (and its alternant -sor ). The association with Latinate vocabulary may impart a learned look to the resultant formations, which often denote machines or other less tangible entities which behave in an agentlike way: descriptor; plexor; projector; repressor; sensor; tractor.
[ ME -o ( u ) r -or-, s. of -or, extracted from -tor -TOR by construing the t as the ending of the ptp. (hence L factor maker, equiv. to fac ( ere ) to make + -tor, was analyzed as fact ( us ), ptp. of facere + -or ); merged with AF, OF -ëo ( u ) r -ator- -ATOR; cf. -EUR ]