You might think it is tough to have a lengthy argument about the meaning of two words. But in the case of Apple and Microsoft, you’d be wrong.

Apple has now fired back in a legal row with Microsoft over whether or not the term “App store” should be protected as intellectual property.

The dispute dates back to 2008 when Apple originally requested a trademark on the term at the launch of the iTunes App Store for iPhone applications. The request covered any form of software sales with delivery over the Internet rather than in physical media.

The trademark application process being a slow-moving beast, there was still opportunity to file objections this January, an opportunity Microsoft took full advantage of. It argued that “undisputed facts” showed that the word “app” (as a contraction of software application) has been in use for 25 years or more, that the word “store” (as, erm, a retail facility) is well established, and that thus it wasn’t possible to trademark the two words together.

Microsoft also argued that app store was widely used to refer to similar services from other providers, and even cited Steve Jobs referring to the Android “app stores” during a conference call.

Apple’s response is to argue that it’s nonsense to look at the individual words: to assess a phrase for trademark purposes you have to take the entire phrase together. Or as the filing states in one section heading, ” Microsoft’s ‘Noun Plus Store’ Test Grossly Oversimplifies the Genericness Test.”

It then trots out a linguistics expert who notes that humans interpret phrases as a whole rather than looking at each word individually, before citing examples of granted trademarks such as “Vision Center” and “Park ‘n’ Fly” that are made up of widely used individual words.

The company also rubbishes the press clippings Microsoft put forward and suggests they are “simply a small, inconsequential subset of how the relevant public uses the term.” It notes that in a database of both written and spoken English use in the US, 88% of the time people mentioned “APP STORE”, they were referring to Apple’s service.

Apple also argues that a study carried out for the Microsoft filing, which put that figure at just 20%, was flawed because it intentionally searched only for use of the term “app store” in lower case, thus excluding many official references to Apple’s service.