An end of the world scenario wherein self replicating nanobots persistently procreate by eating their way through all matter in the universe, leaving nothing behind but an endless sea of nanomachines eating each other.

The creation of the term is attributed to Eric Dexler in 1986, in the book Engines of Creation. Eric warns of a potential scenario where an errant nanomachine could be released and could single-handedly destroy everything, but he also remarks that there is no situation where such a machine would need to be made in the first place. It would not be possible to create such a machine using current day technology.