Open source
Software whose code is publicly available for anyone to use, study, and change. In AI, a fully open-source model releases its code and training details, which is rarer than releasing just the weights.
“Strictly speaking it's open-weight, not open source; the training data is still private.”
See also
Part of the Extended list
Open source is on the Extended list: builder jargon, industry terms, and newer slang for when you want to go further. It entered common use around 2023.