Déjà vu (literally "already seen") is the experience of feeling sure that one has already witnessed or experienced a current situation, even though the exact circumstances of the previous encounter are uncertain and were perhaps imagined.

Déjà vu（法语，意为“曾经见过”）指一种似曾相识的感觉，具体说来就是某人在经历某个场景的时候会很感觉之前曾经经历过完全一样的场景，但事实上这个所谓以前经历过的场景或许并不存在，而且可能只存在于想象当中。

The term was coined by a French psychic¹ researcher, Émile Boirac (1851–1917) in his book L'Avenir des sciences psychiques ("The Future of Psychic Sciences"), which expanded upon an essay he wrote while he was an undergraduate. The experience of déjà vu is usually accompanied by a compelling sense of familiarity, and also a sense of "eeriness²", "strangeness", "weirdness³", or what Sigmund Freud calls "the uncanny". The "previous" experience is most frequently attributed to a dream, although in some cases there is a firm sense that the experience has genuinely happened in the past.

这个词由法国精神研究专家艾米丽•波拉克（1851–1917）在他一本名为《精神科学的未来》的书中首创，这本书是将他本科时的一篇文章扩展后写成的。这种似曾相识的经历通常都伴有强烈的熟悉感，同时还会觉得“怪诞”、“陌生”、“异常”，或者像弗洛伊德所说的“诡异”。那些“以前”的经历多数都来自于梦境，不过有些时候我们都会坚信这个经历真的发生过。

The most likely explanation of déjà vu is not that it is an act of "precognition" or "prophecy", but rather that it is an anomaly of memory, giving the false impression that an experience is "being recalled".

对于似曾相识比较靠谱的解释可不是那些所谓的“先