The Open Source Initiative released their definition of what constitutes Open Source AI:

An Open Source AI is an AI system made available under terms and in a way that grant the freedoms to:

• Use the system for any purpose and without having to ask for permission.
• Study how the system works and inspect its components.
• Modify the system for any purpose, including to change its output.
• Share the system for others to use with or without modifications, for any purpose.

see the full details here

For a quick rundown you can see this article from The Verge. They note this definiation directly challenges Meta’s Llama which has been trumpeted as open source:

Now, for an AI system to be considered truly open source, it must provide:

• Access to details about the data used to train the AI so others can understand and re-create it
• The complete code used to build and run the AI
• The settings and weights from the training, which help the AI produce its results

See more from The Verge

And from Meta Meet Llama 3.1 and Letter from Mark Zuckerberg