Ardor is passion, eagerness, intense enthusiasm. Ardor is the North American spelling, the British spelling is ardour. Ardor appears in the English language in the early fifteenth century, meaning heat of passion or desire. Ardor comes from the Old French ardure, meaning heat, passion and from the Latin ador, meaning a flame, fire, burning, heat.
Some words end in -or in American English and -our in British English. These words come from two languages, French words which end in -ur and Latin words which end in -or. After the Norman conquest of England, French spellings with endings of -our became preferred. In the United States, the 1828 Webster’s dictionary settled on the -or endings of such words, which perpetuated this type of spelling in the United States.
Examples
Always impressive for the sheer volume of his top notes, Mr. Aronica grew in warmth and expressive ardor on Friday, culminating in a deeply affecting rendition of “E lucevan le stelle.” (The New York Times)
Coach Gerelds is inspired to signal his own born-again zeal by being baptized in a local black church, and pretty soon even the trash-talking white coach at crosstown rival Banks High School (played with scene-stealing glee, if not evangelical ardor, by C. Thomas Howell) benefits from what might best be described as a contact epiphany. (Variety)
As Vincent’s stay at the boarding house stretches from weeks to months, his initial obsession with Eugenie fades but he finds a new object for his ardor — her mother. (The Kansas City Star)
The removal of Martin Wheatley as head of the Financial Conduct Authority shortly afterwards was widely attributed to the fact that Mr Wheatley had gone about the business of fining banks for mis-selling with too much ardour. (The Independent)
“He served Indian cricket with exceptional ardour and dedication” (The Bharat Press)
The ‘Oath Ceremony’ reflected the indomitable spirit of the young soldiers, he said, adding that “their ceremonial ardour and salute to the tricolour… inspired patriotic vigour in all present”. (The Statesman)