Google has suffered a setback in its attempts to trademark the word "glass" for its computer-powered spectacles, according to new documents.
The term "Google Glass" has already been trademarked by Google, however an application last year for the word "glass" by itself has been refused by the US Patent and Trademark Office.
The patent refusal was discovered by the Wall Street Journal, who uncovered a letter to the company detailing the objections to the trademark.
"The term GLASS is defined as 'a hard brittle transparent or translucent noncrystalline solid, consisting of metal silicates or similar compounds' (Collins English Dictionary)," the application response states.
"In this case, the mark GLASS would be understood as describing a feature of some of the goods, namely, that some of the goods will incorporate display screens and/or lenses that are or will be made of, inter alia, glass.
"Accordingly, the mark is refused registration under Section 2(e)(1) as merely descriptive."
Google responded to the trademark office with a 1,928-page letter in defense of its case, most of which consisted of Google citing articles that refer to the smartglasses simply as 'Glass'.
Google's trademark attorneys argued that, given the amount of media coverage of the device in recent years, the proposed trademark would not confuse customers.
The descriptive elements of the application response was also disputed, noting that "the frame and display components of the Glass device do not consist of glass at all".
Google do not need the trademark of the term Glass to use it for its product, however future infringements of the name will be difficult to defend against if the company fails in its bid.