I posted somewhere many months ago, the story of how UA bought this variant of the name from Air Canada, which had used a more Frenchified version for its in-between business class product during the 80s. After using it for many years, AC decided to drop First Class altogether, and create Executive Class as its domestic/transborder front cabin product, and ExecutiveFirst as its intercontinental front cabin product. UA then launched Connoisseur Class as its intercontinental business class product when it was relaunched in the early 90s.
The terms as adoped by AC was a bilingual word which, of course, reflected refinement and appreciate of good taste.