Plain meaning
Start with the shortest useful explanation before going deeper.
The condition where an oracle price feed has not been updated within an acceptable time window, making the price data potentially unreliable. Stale prices can lead to incorrect liquidations, mispriced trades, or exploitable arbitrage. Solana DeFi protocols must check the timestamp of oracle updates and reject or pause operations when prices exceed a staleness threshold (e.g., 30 seconds for Pyth feeds).