bullion

Bullion comes from Middle English bulloin or bullioun, from Anglo-Norman bullion, whose origin is obscure. It perhaps traces to French bouillon, with the sense stretched to mean 'melting.'

If the link to bouillon is right, a word tied to bubbling or boiling liquid shifted toward the idea of metal being melted down, eventually settling on refined precious metal in bulk.

It may share roots with bouillon, the French word for broth, through the shared idea of something boiling or melting. A similar-looking Middle Dutch word, boelioen, meaning 'base metal,' is unrelated, coming instead from the French word billon.