If you have found yourself here, you have most likely already come accross the many different guides, frameworks, textbooks and models available.
The fact is, there are as many definitions as there are authors writing about co-production. You can take your pick. As you are here, you are likely seeking a way to have meaningful co-production. A review exploring this issue is highly cited within academic publications because it summarises this issue and proposes a key message:
The definition of co-production will differ depending on the context, therefore it is the consideration of the values and principles of co-production in practice which determines its authenticity.
The core idea of co-production is simple: doing WITH rather than FOR.
Agreeing a definition with those you are seeking to collaborate (if it is needed at all) is perhaps more appropriate than choosing one of the many available. The Co-production Co-MPASS can help to ensure that the values and principles can be considered right from the outset. For those who require a definition for a funding proposal or an academic paper, then this paper may be useful to signpost you to a relevant and useful definition:
Masterson D, Areskoug Josefsson K, Robert G, Nylander E, Kjellström S. Mapping definitions of co-production and co-design in health and social care: a systematic scoping review providing lessons for the future. Health Expect. 2022; 25: 902-913. doi:10.1111/hex.13470