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Foundation model

Core concepts Last reviewed 2026-06-11

Definition A large AI model trained on broad data at scale so it can be adapted to many downstream tasks—drafting, translation, coding—rather than built for a single purpose. Large language models are the most prominent examples.

In more depth

Foundation models serve as a base layer: vendors adapt them through fine-tuning or retrieval-augmented generation to build specialized products, including legal drafting and research tools. Training such models requires data and computing resources only a few organizations can afford, so most AI products are built on a small number of underlying models. Strengths and flaws of the base model—such as a tendency to hallucinate—carry through to the tools built on top of it.

Further reading: Wikipedia.

Related terms

Large language model (LLM)Fine-tuningGenerative AI

About the editor: MHSB Solutions, Research desk. MHSB Solutions is not a law firm. This glossary is educational information, not legal advice.

Educational information, not legal advice. AI terminology and tools change quickly; definitions reflect usage as of the last-updated date. For what bar associations and courts actually require of lawyers using AI, see legalaicompliance.help and consult a licensed attorney in your jurisdiction.