It's no surprise that Google and other companies try to trademark the names of their products to keep other firms from coming in and naming products similarly. Google has been trying to trademark the word "Glass" to go along with its slick wearable computing device called Google Glass. Trademarking that word is proving to be a very difficult task for Google.
Google was able to trademark the specific term "Google Glass" but it wanted to trademark the more generic term used by many to describe the glasses. Trademarking the simple term "Glass" is getting pushback from the US Patent and Trademark office with two major objections. One of those objections is that "glass" is too similar to existing trademarks and trademark requests that have already been field.
The USPTO says that the similarity would create a confusion risk for consumers. Google apparently filed for the trademark on "Glass" using a specific font and the second issue according to the USPTO is that even with that special font, the trademark is merely descriptive. That makes the term generic and generic descriptions can't be protected with trademarks under federal law.
The USPTO has been guilty of granting trademarks on generic terms in the past. A perfect example is granting the trademark for the word "Candy" to the makers of the game Candy Crush. Interestingly, the backlash to King trademarking Candy led to the firm seek to abandon the trademark. Naturally, Google disagrees with the USPTO arguing that "Glass" isn’t descriptive because the product isn't made from glass, but is made from titanium and plastic. Google is still fighting for the trademark and even if it is unsuccessful in protecting the word "Glass", it can still use it in marketing. Not having the trademark would make it harder to protect its product.