What is the Difference between a Television and Monitor?

I wrote a review last week about a Westinghouse 1080p LCD monitor. This is a television that I referred to as a monitor, but why? While it is does feature LCD technology -the same stuff in most PC monitors - it is not built as to serve only as a PC monitor. In fact, at 42" it is made primariy for television viewing. Still, there is a subtle difference between a television and a monitor that might make a difference in your future consumer electronics purchases.