OMG I had to Google that. Being reasonably old and from the UK I tend to use "disc" to describe all round flat items, including magnetic storage media, from before CD being a thing. I had no idea that the Phillips "Compact Disc" trademark had actually stuck for optical media.
So a blu-ray, despite not being a CD, uses the European "disc" spelling despite other storage deriving from IBM's work in America often being called "disk". Had optical media been invented in the States they would all be called "disk" which for me makes it a bizarre convention, though still makes more sense than "fewer" vs "less".
Thanks for the education, though being British and stuck in my ways I will no doubt continue to just use "disc"
