Can I just ask, what is everyone's definition of Middle Of the Road?

The other day, my music teacher asked if anyone knows what it was used to describe. I said stuff like Embrace, David Gray etc.
He said I was completey wrong. He said MOR is stuff like Cliff Richards, Will Young etc...

I'm pretty sure I'm right, seeing as the NME (who apparently created the term), used it in Embrace's album review. Am I right?