Are you a teacher, or education professional?
Educators always point this out to me.
CD-Readable, yeah that is it, like ROM, Read Only Memory
It is not a CD-ROM (CD-Read Only Memory) because you can Write to it in the first place. So they (whoever THEY are) just shortend it to CD-R
As far as I remember, CD-R (recordable) came about as the name because they were originally used for music. Typically, when you are talking about putting music on some sort of media, you are recording it.
CD-RW (re-writable) came along later, and was more aimed at data. Typically, when you are talking about putting data on to a storage media, you are writing it.