The term déjà vu was coined in 1876 by the French philosopher Emile Boirac. It is the overwhelming sense that you have already experienced something before. But there are other, lesser known, phenomena which are thought to be related.
Jamais vu - translated as "never seen", this is the sense that something which should be familiar is alien, for example a common word which suddenly seems strange.
Presque vu - translated as "almost seen", this is the sense of being on the edge of an epiphany or realisation, for example recalling a memory.
Déjà entendu - translated "already heard", this is the sense of feeling sure you have heard something before, like a snippet of conversation or a musical phrase.