Catalyst, noun: A person or thing that precipitates an event; "She acted as a catalyst for change." Or, a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change. Also, the subtitle (or something) of the next Mirror's Edge.
The truth is that we don't know how Catalyst relates to Mirror's Edge, but one way or another, it quite clearly does. IGN pointed out earlier today that EA has filed a trademark, viewable here, for "Mirror's Edge Catalyst," which covers "computer game software; downloadable computer game software via a global computer network and wireless devices; video game software," as well as "entertainment services, namely, providing an on-line computer game."
That in itself doesn't mean much; companies file and fight over trademarks all the time, and sometimes the filings are actually fakes intended to stir up excitement (and then anger) amongst the fan base. But shortly after the report of the trademark filing came to light, the image above hit the official Mirror's Edge Twitter feed, making it clear that Catalyst is both real and relevant.
There were suggestions, prior to the "Catalyst" tweet, that the trademark filing could be unrelated to Mirror's Edge 2, and may perhaps be for something like a mobile game tie-in instead. But for EA to use it for the first tweet out of the Mirror's Edge account since January, and only the second of 2015, makes me think that it has to be the real deal.
As always, we've reached out EA for more information and will update if and when we receive a reply. But with E3 just around the corner, I think there's a good chance we'll just have to wait.