It seems like a reasonable definition to me as long as it's clear that "the computer" means that specific computer. e.g. In this definition, if you use a PC at

It seems like a reasonable definition to me as long as it's clear that "the computer" means that specific computer. e.g. In this definition, if you use a PC at your office and a laptop at home for non-work stuff, your work PC is being used by a "professional" and your home laptop isn't.