Wikipedia's cycle definition, however matches DF's so far:
http://en.wikipedia.org/wiki/Software_release_life_cycle#Alpha
The alpha phase usually ends with a feature freeze, indicating that no more features will be added to the software.
(Emphasis added)
Usually: There are exceptions.
Ends: Features are usually still added during Alpha.
I believe that another gentleman who's also done some work in the Industry stated that most of the 'exceptions' to the phase definitions are exceptions due to poor management and application of standards. The feature freeze at the end of Alpha is there for a reason and that reason is important. When your features are still dynamic you cannot do the work that you are actually MEANT to do in beta, which is the finalisation of code - obviously, because the functionality is still in flux.
Does that mean that all projects achieve a complete feature freeze at the Alpha milestone? No - because many projects fail to adhere to standards. Sometimes the gamble works, in which case we say that non-rigid adherence to process leads to flexibility which improves the quality of the project. Sometimes the gamble fails, pushing back deadlines and failing milestones in which case we attribute the failure to meet expectations to poor management. Sometimes it causes the project to collapse and we just say Duke Nukem Forever.
By your argument one could say:
Insulation in residential dwellings should not include asbestos
should not: It could.
Ends: Companies can use asbestos when constructing residential dwellings
Using these two definitions, we can say that DF simply went into an early alpha stage, since pre-alpha ended with the first public release, and there hasn't been a feature freeze yet, so it most certainly hasn't progressed past it.
We could say that, but as large chunks of the functionality are incomplete, it would be more accurate to say that both the earlier versions and this version too are best defined as 'Pre-Alpha'. Pre-Alpha isn't a real phase, it's simply a term used to let those interacting with the product know that it hasn't reached the Alpha Milestone yet.
http://en.wikipedia.org/wiki/Software_release_life_cycle#Impact_of_the_World-Wide_Web
states that the term "beta" is now much more general than before, so a precise definition will not apply to every single product, especially newer ones.
Ugh. The word Beta has now acquired a Marketing connotation whereby it is used to describe a phase of the endcycle where the users get to have an early peek at the project. Beta used to be a simple, single definition, phase but has now grown into several distinct flavours.
Starting with the Closed Beta - which is a version of the game distributed inhouse to be assessed by solely inhouse personnel. It might also be demoed, with supervision, to selected media outlets at this time. It is not to be left in unsupervised hands of any out of house persons at this time, however, as it is typically VERY fragile. Most of the testing is done using Closed Beta versions.
Open Restricted Beta - This is when the game is first released to a very small number of out of house persons, including members of the public. This is traditionally the LAST phase where serious testing is done on game features - although game balancing and networking experience is focused on in the next phase.
Open Beta - Everyone and their dog gets access now. Typically the product is about 99% complete, since a seriously broken game won't be shown to journalists, never mind the public. Mostly the focus is game balancing, exploits and network performance. The inevitable real bugs that are discovered at this point are always a MAJOR headache to a team that has virtually NO time left to fix them. For this reason, many bugs of the B class and down that discovered in Open Beta are left unfixed until post-release patching, to the great ire and confusion of those Open Beta participants who actually consider themselves bona fide testers.
It may be true that the definition of Beta is becoming fungible when Marketeers talk to Journalists or the Public, but when the Development Team is talking about Beta internally it is usually referring to the Closed Beta phase, since it often has little control over the point at which a Closed Beta turns Restricted Open or Open.