A federal judge on Wednesday rejected Apple's claim of false advertising for Amazon.com to refer to its online shop for mobile gadget applications as an "app store".
"Apple has failed to establish that Amazon made any false statement of fact that actually deceived or had the tendency to deceive a substantial segment of its audience," US District Judge Phyllis Hamilton said in her ruling.
"The mere use of 'Appstore' by Amazon to designate a site for viewing and downloading/purchasing apps cannot be construed as a representation that the nature, characteristics, or quality of the Amazon Appstore is the same as that of the Apple App Store."
Apple in 2008 launched its App Store, which is stocked with mini-programs for iPhones, iPads, and iPod touch devices.
Amazon in late 2011 opened its "Appstore," which sells applications tailored for Android-powered mobile devices for the Seattle, Washington-based retail giant's Kindle Fire tablets.
Apple sued Amazon, claiming its rival was engaging in false advertising as well as trademark infringement.
US officials are still considering Apple's application to trademark the term "App Store," but that did not deter the company from pressing its case in Hamilton's courtroom in the California city of Oakland.
Software titan Microsoft is among the companies that have weighed in against letting the Cupertino, California, company have a trademark giving it the exclusive right to call a mobile applications market an "app store".