Mendip I had to ask him the same thing. It stands for "cathode ray tube".
I think he was trying to be funny insinuating that I could see his oversize pictures because I had an old monitor.
He won't admit that its his problem not mine I just have to put up with his inability to understand that not everyone has the latest and greatest.
My computer monitor is barely 6 months old and the display resolution is set the same as his monitor but there you are a manager who blames everyone but himself.