neutralino
n.— «Neutralinos are (or, at least, are predicted to be) the lightest and most stable of these new particles. And their stability means they may also solve a cosmological mystery, which is that a quarter of the universe seems to be made of dark matter that can be detected only by its gravitational interactions. Many physicists think this dark matter is made largely of neutralinos. That neutralinos feel gravity but not electromagnetism makes them hard to detect. (They also feel the weak nuclear force, but that, as its name suggests, is little help.)» —“Merry Christmas, Dr Heuer” Economist (United Kingdom) Dec. 19, 2007. (source: Double-Tongued Dictionary)