A synthetic asset in DeFi refers to a tokenized representation of an underlying asset, such as stocks, commodities, or fiat currencies, that is created on a blockchain platform. Synthetic assets are designed to mimic the price and value of the real-world assets they represent, allowing users to gain exposure to these assets without actually owning them. These tokens are usually collateralized by other assets in the DeFi ecosystem and can be traded and exchanged like any other digital asset.