Copyrights and Patents: How to Copyright a Name
Simply put, you can't. To protect a business name within your industry, you would apply for a trademark.
Copyrights can be obtained for things of an artistic nature. This includes, of course, poetry, films, sculptures, music, fiction, etc. But can also include things that may not necessarily seem "artistic" in the general sense of the word. Copyrights can also be obtained for advertising copy, games, software programs and blueprints, to name just a few.
To protect a business name within your industry, you would apply for a trademark.
Trademarks can be names of products or services, logos, slogans, packaging and even sounds and smells. In essence, a trademark can be almost anything that is used to identify a particular product or service. Registering a trademark grants the owner exclusive rights to the mark within the specified industry.
Of course, it's necessary to research the mark comprehensively prior to filing to ensure that there is no possibility of infringing upon another party.