I mean... can I use the term bitcoin freely in my business ?
You need to go to:
http://www.uspto.gov/trademarks/index.jspAnd conduct a Trademark Search.
The term "Bitcoin" was actually trademarked for about a month in connection with cryptocurrency but was abandoned.
"Bitcoin" is trademarked in connection with certain goods and services but I'd bet that for must uses due to the ubiquitous nature of the term that subsequent registrations would not hold up.
My $.02.
Pretty certain this is correct. Good post.