What is the correct way to use a copyrighted term legally on a site?

My company wants to sell a product called DMA (Designated Marketing Area) Maps. DMA's are defined by Nielson and the term is well known in the B2B community, and the term had been copywrited by them. We want to use the term DMA to define areas that we have defined with our own data. Would we be able to use the term DMA with a copyright symbol and a disclaimer at the bottom stating These DMA boundaries are not defined by Nielson. Our DMA reference boudaries have been created with data from Intelligent Direct Inc." Or do we have top come up with a slightly altered version of the term like Designated Marketing Regions? 

Alasdair Taylor's answer to What is the correct way to use a copywrited term legally on a site? (1394209474)

I'm guessing that this is really a question about US law:

http://www.nielsen.com/intl-campaigns/us/dma-maps.html

Our expertise is in English law, so I don't think we can help here.

NB it sounds more like a trade mark question than a copyright question.