It can also mean something Netflix has put money into as well. Netflix is a media acquisitions company, not a studio, so for their own original series they give another company money to make it.
For shows like "Peaky Blinders," they've probably bought the rights to be the only American broadcaster for it and as such they're acting as curators of content they think belongs on their "channel."
The problem is Hulu decided it would be great to have lots of original content but didn't have the budget to produce it. So they scoured the world for shows that didn't have US deals that they could acquire and rather than calling them Hulu Exclusives started calling them Hulu Originals. I think it's a little disingenuous for them to call that a Netflix Original, but I get it, it's their branding to say they have some sort of stake in whatever the content is.
In the strictest sense it's not who produces the content but who commissions it and pays the bulk of the production costs. So in traditional TV House was a Fox original despite being producers by NBC Universal and Modern Family is an ABC original despite being produced by Fox.
Netflix for a while stuck to the proper Original definition, it was only content that they commissioned and paid the majority of the budget for but recently they have seen Hulu get away with it and jump on the bandwagon.
Once they own it, it can be released with whatever they want to state.
We see this with "Arrested Development", "Trailer Park Boys", and many more. A Netflix Original is no different than A Lions Gate Production they own the rights, they can state what they want.
In general they are at least buying better quality shows than Hulu but it's still misusing the original term. In addition to "Peaky Blinders" they have also done it with "Derek", "Happy Valley", "Southcliffe", "Borgia", "The Fall" and in some regions even "Dusk To Dawn: The Series". I'm probably missing some as well. But here is a partial list of their OC:
- House of Cards
- Hemlock Grove
- Orange Is the New Black
- Marco Polo
- Stranger Things
- The Get Down
- The Crown
- A Series of Unfortunate Events *
On the DVD/BD front even on broadcast TV its standard that the production company retains rights to Home Media and International releases.
The broadcaster only has broadcast rights in the local territory.
Its why "House of Cards" isn't on Netflix in France because with no Netflix at the time the producer was free to sell the international broadcast rights which they did giving Netflix a problem now they have launched.