When it comes to trademarks, Facebook is proving to be a bully. It is going after Teachbook in court for using a similar name, and already forced Placebook to change its name. But that is only half the story.

It is not just the word “book” at the end of a company or product name that Facebook might object to. If it has its way, the word “Face” at the beginning of a name might also bring out its lawyers. In fact, Facebook is currently trying to register the word “Face” as a trademark. (It already owns the trademark on “Facebook”). Facebook took over the trademark application for “Face” from a company in the UK called CIS Internet Limited, which operated a site called Faceparty.com. Presumably, Facebook bought the application sometime around November, 2008, which is when its lawyer started dealing with the USPTO.

However, at least one person is objecting to this trademark: Aaron Greenspan. Yup, that Aaron Greenspan, Mark Zuckerberg’s classmate at Harvard who laid a claim to helping create Facebook, which he later settled. Greenspan now has his own company, Think Computer, which is behind the mobile payments app called FaceCash (watch the TCTV interview with him).

If Facebook gets the trademark for the word “Face,” that could spell trouble for FaceCash. “The possible registration has implications for my company (not to mention hundreds of others, including Apple, Inc.), so I’ve decided to ask the USPTO for an extension of time to oppose it,” he explains in an email. Apple, of course, owns the trademark to “Facetime,” the video calling feature on the latest iPhones.

Although Greenspan owns the trademark to “FaceCash”, he wants to protect his ability to use the word “face” in future products. He also wants to make sure Facebook won’t go after him. Given it’s track record of vigorously defending its trademarks (which it is encouraged to do by the law or else risk losing them), that could become a very real possibility.

Getting an extension of time to file an objection is not the same as actually blocking the trademark. But “face” is a pretty generic word and Facebook doesn’t actually use it on its own, only in combination with “book.” If Facebook doesn’t get “face,” maybe it will have better luck with “like.” It has at least 14 applications to trademark that word as well.