AI Governance Engineer
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Open-weight model

By Updated

A model whose trained weights are published for download under a licence that may be permissive, copyleft, use-restricted or custom 1. Open weights are not open source; the deployer produces almost all the evidence (hashes, scans, evals, red team) and must honour the licence and any acceptable-use policy.

Developed in
ch. 15, Open-weight licences
ch. 18, Open-source carve-outs and their limits
Chapters
ch. 15, Deployment · ch. 18, EU AI Act
Contrast with
Responsible-AI licence (OpenRAIL)
Source
1 numbered reference, listed below

Where it is used

3 chapters of the Body of Knowledge use the term. Each link opens the first section that does.

Open-weight model: mentions per chapter4 mentions of the term across 3 of the 23 chapters of the Body of Knowledge; the chapters the glossary cross-references are drawn solid.Cross-referenced chapterOther chapterCross-referenced, not named12 Governance Program: 1 mention12 Governance Program115 Deployment: 1 mention15 Deployment118 EU AI Act020 Existing Law: 2 mentions20 Existing Law2No mentions in the other 19 chaptersSource: the Body of Knowledgev0.5.0
Open-weight model: mentions per chapter4 mentions of the term across 3 of the 23 chapters of the Body of Knowledge; the chapters the glossary cross-references are drawn solid.Cross-referenced chapterOther chapterCross-referenced, not named000102030405060708101112 Governance Program: 1 mention112131415 Deployment: 1 mention1151617181920 Existing Law: 2 mentions220212223Source: the Body of Knowledge v0.5.0
Mentions per chapter How often each chapter names the term, with the chapters the glossary cross-references drawn solid. The longest bar is where to read the term in use; bars spread across many chapters mark a term that runs through the discipline.
Mentions as a table
Mentions of Open-weight model per chapter
ChapterMentionsCross-referenced
00 Preface0No
01 Definition0No
02 Why Now0No
03 Values & Principles0No
04 The Stack0No
05 Patterns0No
06 The Role0No
07 Maturity Model0No
08 Regulatory Map0No
10 Reading List0No
11 AI Defined0No
12 Governance Program1No
13 Risk Management0No
14 Development0No
15 Deployment1Yes
16 Fairness & XAI0No
17 Incidents0No
18 EU AI Act0Yes
19 Privacy & AI0No
20 Existing Law2No
21 AI Laws Worldwide0No
22 Principles & Standards0No
23 AI Agents0No
Open-weight model: related terms and patternsThe term at the centre; related terms on solid edges, the terms it is contrasted with on dashed edges, and the patterns that use it most in the colour of their layer.RelatedContrastOpen-weight modelRelated terms (3)Acceptable-use policy (AUP) · RelatedAcceptable-use policy (AUP)Deployer · RelatedDeployerEvals · RelatedEvalsContrast with (1)Responsible-AI licence (OpenRAIL) · ContrastResponsible-AI licence
Open-weight model: related terms and patternsThe term at the centre; related terms on solid edges, the terms it is contrasted with on dashed edges, and the patterns that use it most in the colour of their layer.RelatedContrastRelated terms (3)Acceptable-use policy (AUP) · RelatedAcceptable-use policy (AUP)Deployer · RelatedDeployerEvals · RelatedEvalsContrast with (1)Responsible-AI licence (OpenRAIL) · ContrastResponsible-AI licenceOpen-weightmodel
The term's neighbourhood Terms related to this one on solid edges, terms it is often confused with on dashed edges, and the patterns that use it most in the colour of their layer. Follow a dashed edge to check the distinction before you use either term.
Neighbourhood as a table
Neighbourhood of Open-weight model
FamilyItemRelation
Related termsAcceptable-use policy (AUP)Related
Related termsDeployerRelated
Related termsEvalsRelated
Contrast withResponsible-AI licence (OpenRAIL)Contrast
  • Acceptable-use policy (AUP)

    The staff-facing rules for using AI tools: which tools are approved, which data classes may go where, duties to review and disclose outputs, logging…

  • Deployer

    Under the EU AI Act, whoever uses an AI system under its own authority, other than in a purely personal, non-professional activity.

  • Evals

    Automated tests of a model's or agent's behaviour (capability, safety and adversarial), run as controls, not as one-off research.

Sources

  1. [1] Llama 3.1 Community License Agreement (an example of an open-weight licence with an incorporated acceptable-use policy and attribution terms). Meta. 2024-07-23. https://github.com/meta-llama/llama-models/blob/main/models/llama3_1/LICENSE (verified: primary)

Definitions of legal terms paraphrase the cited text, which governs. Dated statements are as of .

Cite this term

García Aibar, J. (2026). Open-weight model. In AI Governance Engineering: The Thesis & Body of Knowledge (v0.5.0), Glossary. https://doi.org/10.5281/zenodo.22956197. https://aigovernanceengineer.com/glossary/open-weight-model. CC BY 4.0

BibTeX

@misc{aige2026openweightmodel,
  author  = {Jorge García Aibar},
  title   = {{Open-weight model}},
  note    = {Glossary, AI Governance Engineering: The Thesis \& Body of Knowledge, version 0.5.0},
  year    = {2026},
  doi     = {10.5281/zenodo.22956197},
  url     = {https://aigovernanceengineer.com/glossary/open-weight-model}
}