Anti-time is a chronometric plane inverse to regular time.
The Devron System IncidentEdit
An eruption of anti-time caused by the explosion of the USS Pasteur's warp core and a weakened time-space continuum due to an inverse tachyon pulse from the Pasteur in 2395 and USS Enterprise-D 2364 and 2370 occurred in the Devron system . The eruption enlarges as one moves back in time. This means that in the distant past the eruption actually disrupts the origin of life on Earth. (TNG episode: "All Good Things...")
It should be noted that the Devron system is about 33 light-years from Earth and that the anomaly would have destroyed life in a sphere 66 light-years in diameter. However this is called into question by Q’s words that the anomaly is the size of the quadrant which means 4 billion years ago the Devron system was half a quadrant away from Earth. (This is possible due to stellar drift).