In his review of Mindfulness, Miguel de Beistegui revisits the issue of translating Heidegger's neologisms. He has this to say about Ereignis.

Is Ereignis one of those words that we should leave untranslated? If we are to listen to Heidegger, the answer is yes, since he declared the word untranslatable. There is already a precedent in that respect: Dasein is usually left untranslated in English. But the problem is that Ereignis is a word that contains many other words within it, and especially the verbs ereignen, ent-eignen, übereignen, and zueignen. In a way, and in certain contexts, we find ourselves forced to translate Ereignis, because of the many other verbs and names associated with it. Is "en-owning" the correct translation, then? Not believing that the prefix en- does any work in that neologism, I can't support such a translation. In addition, how can one forget entirely the fact that Ereignis normally means "event," and that there are very good reasons to believe that, by understanding Sein verbally, and transitively, Ereignis does designate something like the recurrent event of being, as the giving or granting of ownness or properness? This is why I suggest "event of ap-propriation" as a possible translation. According to the OED, "to appropriate" means "to make something over to someone as his own." This is the sense that we need to bear in mind. Ap-propriation signals the granting of the own, of the proper. The other, more common sense of the term, on the other hand, needs to be ignored, for Heidegger's Ereignis does not involve the act of taking possession of something for one's own. Ereignis can be understood as an event only to the extent that it is a granting of the proper or the own, and not in the sense of an actual event, no matter how great, taking place in space and time (for Ereignis is also the event or the unfolding of time-space, the advent of History). It's an event that is forever recurring, and recurring differently: the different ways in which this event recurs are what Heidegger calls "epochs." In the case of the event of ap-propriation, I believe hyphenation is justified: it emphasises the process by which man and being are mutually and reciprocally brought into their own, and erases the temptation to understand appropriation as a form of violent reduction of something external and different to something like a pre-given and self-enclosed identity. At the same time, it retains the link -- crucial, in my view -- with the ordinary sense of the word, that is, the event. Most of all, it has the advantage of evoking something that is not altogether unfamiliar to the Anglophone ear.

  ¶ 3:24 PM