In Mac OS X, the terms “ejecting” and “unmounting”, as they relate to removeable media, are considered interchangeable by most end users. Most people will talk about “ejecting” their USB flash drive, even though this doesn’t cause the drive to pop out like a CD or DVD. Apple explain this thus:
…Ejecting a volume may not mean that it is physically ejected from the computer, but that it is no longer available (mounted) on the desktop or in a Finder window.