1. A feeling of having experienced something before even though in fact it is the first time that it has been experienced: Stanley had an eerie sense of déjà vu when he went to visit an old castle in England because he felt that he had been there long ago even though he was from California and had never been to England before.
2. Boredom that results from something that has happened many times: There was a man who felt he had a permanent sense of déjà vu and he refused to watch TV or read a newspaper because he claimed to have seen everything before. When he went out walking he said the same birds sang in the same trees and the same cars drove past at the same time every day.
3. Etymology: from French déjà, "already" + vu, "seen"; from Latin videre, "to see".